Baking School In-Depth: Triple-Chocolate Mousse Cake

triple-chocolate mousse cake

Inspired by chocolate entremets found at the finest French restaurants and pâtisseries, this Triple-Chocolate Mousse Cake delivers an array of chocolaty elements, from cake to mousse to mirror glaze, in one showstopping package. Designed to delight all the senses, this cake combines the rich flavors of chocolate with an assortment of complementary textures, from a light, airy mousse to a creamy White Chocolate Filling. This month’s module is certainly a labor of love, but with the help of step-by-step images and expert tips and tricks, you’ll be making mousse, layering cakes, and creating a mirror glaze like a pro. Click here to download a printable PDF of this lesson, or keep scrolling to view our digital lesson.

Join us Monday, August 8, 2022, at 5 p.m. PT for our Baking School In-Depth class! Brian Hart Hoffman will be diving into this recipe, talking all things chocolate cake and answering all of your recipe-related questions, so, chocolate lovers, be sure to join. Register here!

Ingredient Breakdown

Great recipes require great ingredients. Here’s how each of our recipe’s simple ingredients contributes to making the most decadent Triple-Chocolate Mousse Cake.

All-purpose flour: For the delicate crumb of this rich chocolate cake, a flour that balances between soft and hard is needed. All-purpose wheat flour serves as the perfect solution, with a protein content that typically ranges from 10% to 12%. At this level, the cake is tender but structured enough to trim and stack.

Baking powder: Comprised of baking soda, powdered acid or acids, and a starch, most baking powders are double-acting, meaning the reaction occurs twice, using two different acids. The first is a very quick reaction that occurs when baking powder is combined with a liquid, aerating the batter. The second reaction is slower-acting, occurring when heated and baked.

Kosher salt: We bake with kosher salt because, unlike most commercial salt, it doesn’t contain iodine, making it taste purer and more palatable. Also, the salt crystals are larger. Table salt is much finer, so you would use half of what a recipe with kosher salt calls for.

Hot brewed coffee: Coffee plays two roles in our recipe, working to enhance the rich chocolate flavor of the cake while also helping to “bloom,” or hydrate, the cocoa powder. As the cocoa is mixed with the hot coffee, larger clumps dissolve, making a smooth paste that’s easier to mix into the batter. Blooming cocoa powder also helps release flavor particles, making for a richer, more intense chocolate flavor. For those who don’t love coffee, no need to fret. Using a medium or light roast coffee gives the cake an incredibly mild, barely noticeable coffee flavor, but for those truly averse, boiling water will work just as well substituted 1:1. For a stronger coffee flavor, look no further than dark roast.

Dutch process cocoa powder: Dutch process cocoa powder is treated with an alkaline solution of potassium carbonate to make it milder and less acidic in flavor and darker in color. We opt for Dutch process cocoa because it is slightly less astringent in flavor than natural cocoa powder, so it makes an intense but not bitter-tasting chocolate cake.

Whole milk: Also referred to as full-fat milk, whole milk is cow’s milk that hasn’t had any of its natural fat content removed. Whole milk is typically 3.5% milk fat, making it rich with a slightly thicker consistency. The added fat and moisture of whole milk help create a tender, richer cake.

Light brown sugar: Sugar is a hygroscopic ingredient, which means it absorbs moisture. So, when used in this recipe, it keeps your cakes moist longer while also adding a slight caramelized flavor with its 3.5% molasses content.

Neutral oil: Unlike cakes made with butter, oil cakes tend to bake up loftier with a more even crumb that stays moist and tender longer. That’s because butter is only about 80% fat and cools solid, whereas cooking oil is 100% fat and completely liquid. Oil incorporates easier into batters, and because of its liquid state, keeps cakes moist even as they cool. We use vegetable oil for our batter, but canola oil will also work well.

Egg: Eggs bring richness through their yolks and moisture through their whites, but they also help leaven baked goods. In this recipe, we use one large egg for leavening, flavor, richness, and structure.

Vanilla extract: Vanilla complements and enhances the cocoa notes in our recipe.

Anatomy of an Entremet

An entremet is a cake made up of multiple components assembled into layers, covered in mousse, enrobed in glaze, and decorated with everything from fresh fruit to chocolate shavings. Though entremets come in a variety of colors, flavors, shapes, and sizes, we chose to highlight a classic entremet flavor profile: chocolate. Our cake is made up of the following elements, each requiring a precise execution, a standard in French pastry:

  • Chocolate Devil’s Food Cake: Beautifully balanced between light and rich, with a deliciously delicate crumb, this classic chocolate cake works as the base for our entremet-inspired cake.
  • White Chocolate Filling: A mixture of cream cheese, sugar, white chocolate, and heavy whipping cream, our White Chocolate Filling is sweet, creamy, and incredibly decadent. White chocolate doesn’t contain the cocoa solids found in other forms of chocolate but instead uses cocoa butter, sugar, milk products, and flavorings to achieve its signature sweet, creamy taste.
  • Chocolate Mousse: Airy and fluffy, our mousse relies upon whipped egg whites and cream to achieve its light texture. Unlike other mousses that may call for gelatin or another thickening agent to help set the mousse, this one relies upon melted chocolate, which, as it cools, helps the mousse set firm. Though mousse requires attention to detail from start to finish, the key is not overmixing once your aerated ingredients are added.

    Timing is also very important for mousse. If components are too hot or cold it will mess you up. Make sure you are prepared and have everything measured before you begin.

  • Chocolate Mirror Glaze: Super smooth, reflective, and glossy, mirror glaze gives cakes an undeniably polished, elegant look. In order for mirror glaze to work, it needs to be liquid as you pour it over your cake but set when it touches the cake. For more information on mirror glaze, see “Mirror, Mirror” below.

 

Tool Talk

To make this cake, you’ll need the proper tools

Offset spatula: The ultimate smoothing tool, an offset spatula will help you spread filling, smooth mousse, and evenly coat your cake in mirror glaze.

Thermometer: Multiple elements of this recipe rely upon proper temperatures and timing. An instant-read thermometer will ensure that each element comes together seamlessly.

Springform pan: A springform pan allows you to construct a multilayered cake without worrying about trying to turn it or lift it out of the pan, while also providing the necessary depth to hold all of the cake’s components and layers. The detachable sides make the transfer from pan to cake board much quicker and easier. We used Williams Sonoma’s Goldtouch® Pro Nonstick Leakproof Springform Cake Pan.

Kitchen torch: A kitchen torch provides a perfectly slight burst of heat to release your frozen cake from the surrounding springform pan

Rimmed baking sheet & wire rack: When it comes time to glaze your cake, a rimmed baking sheet and a wire rack will save you a lot of time on cleanup, catching any excess glaze without forcing it to pool at the base of the cake. For this recipe, we used Williams Sonoma’s Goldtouch® Pro Nonstick Non Corrugated Half Sheet with Cooling Rack. A commercial-quality pan crafted of aluminized steel, this combo features Williams Sonoma’s signature Goldtouch® Pro nonstick coating—its most advanced nonstick finish—for easy release and quick cleanup.

 

Triple-Chocolate Mousse Cake

Chocolate lovers, rejoice! This beautifully layered Chocolate Mousse Cake combines layers of rich chocolate cake, lusciously sweet and smooth White Chocolate Filling, and fluffy Chocolate Mousse all concealed under an undeniably elegant Chocolate Mirror Glaze. This shiny showstopper is a special occasion in and of itself.

Triple-Chocolate Mousse Cake
 
Makes 1 (9-inch) cake
Ingredients
  • ¾ cup (94 grams) all-purpose flour
  • 1 teaspoon (5 grams) baking powder
  • ¼ teaspoon kosher salt
  • ½ cup (120 grams) hot brewed coffee
  • ⅓ cup (28 grams) Dutch process cocoa powder
  • ⅓ cup (80 grams) whole milk
  • ¾ cup (165 grams) firmly packed light brown sugar
  • ¼ cup (56 grams) neutral oil
  • 1 large egg (50 grams)
  • 1 teaspoon (4 grams) vanilla extract
  • White Chocolate Filling (recipe follows)
  • Chocolate Mousse (recipe follows)
  • Chocolate Mirror Glaze (recipe follows)
Instructions
  1. Preheat oven to 325°F (170°C). Spray 2 (8-inch) round cake pans with baking spray with flour.
  2. In a large bowl, whisk together flour, baking powder, and salt.
  3. In a medium bowl, whisk together hot coffee and cocoa until smooth. Whisk in milk. Add brown sugar, oil, egg, and vanilla, and whisk until combined. Gradually add flour mixture, whisking just until combined. Divide batter between prepared pans (about 300 grams each). (Batter will be thin.)
  4. Bake until cake pulls away from sides of pan and a wooden pick inserted in center comes out clean, about 15 minutes. Let cool completely in pan.
  5. Level cooled cake layers, if desired. Place 1 cake layer in center on base of a 9-inch springform pan without sides.
  6. Place White Chocolate Filling in a large pastry bag, and cut a 1-inch opening in tip. Pipe an even layer on top of cake layer in pan, smoothing with an offset spatula. Top with remaining cake layer. (Make sure filling is smooth and does not stick out past sides of cake.) Place sides on springform pan; cover and refrigerate while preparing mousse.
  7. Place Chocolate Mousse in a large pastry bag, in batches as needed, and cut a 1-inch opening in tip. Pipe around outside edges and on top of cake, smoothing with an offset spatula. (Springform pan will be full and mousse will come to the top). Cover and freeze until firm, about 4 hours or up to overnight.
  8. After preparing the Chocolate Mirror Glaze and as it is cooling, using a small kitchen torch or a hot towel, heat sides of springform pan. Remove sides of pan, and using a large spatula, transfer cake to a 9-inch cake board. Using a hot, dry spatula, smooth edges and top as needed. Freeze until glaze reaches correct temperature.
  9. Line a rimmed baking sheet with plastic wrap; place a wire rack on top. Place cake on prepared rack. Pour Chocolate Mirror Glaze over cake, making sure sides are completely covered. Using a large spatula, swipe top of cake once to remove any excess glaze. (Do not do this more than once; it will start to set and will not be completely smooth anymore.) Refrigerate until glaze is set and cake has thawed in center, about 3 hours. Serve cold.

White Chocolate Filling
 
Makes about 1⅔ cups
Ingredients
  • 4 ounces (113 grams) cream cheese, softened
  • 1½ tablespoons (18 grams) granulated sugar
  • 2 ounces (57 grams) white chocolate, melted and cooled (95°F/35°C)
  • ½ cup (120 grams) cold heavy whipping cream
Instructions
  1. In the bowl of a stand mixer fitted with the paddle attachment, beat cream cheese at medium speed until smooth, about 1 minute. Add sugar, and beat at medium-low speed until sugar is melted and mixture is smooth, stopping to scrape sides of bowl. Add melted white chocolate, and beat until well combined. With mixer on medium-low speed, add cold cream in a slow, steady stream. Thoroughly scrape sides of bowl. Slowly increase mixer speed to medium, beating until stiff peaks form, about 1 minute.

Chocolate Mousse
 
Makes 6 cups
Ingredients
  • 1¼ cups (300 grams) cold heavy whipping cream
  • 2 teaspoons (8 grams) vanilla extract
  • 12 ounces (340 grams) 60% to 70% cacao bittersweet chocolate, chopped
  • 2 tablespoons (28 grams) unsalted butter
  • 6 large eggs (300 grams), separated
  • ¾ cup (150 grams) granulated sugar, divided
Instructions
  1. In the bowl of a stand mixer fitted with the whisk attachment, beat cold cream and vanilla, slowly increasing mixer speed to medium-high, until stiff peaks form, about 2 minutes. Transfer to a medium bowl; cover and refrigerate until ready to use. Clean bowl of stand mixer and whisk.
  2. In the top of a double boiler, place chocolate and butter. Cook over simmering water, stirring occasionally, until melted and smooth. Let stand until ready to use.
  3. In a large heatproof bowl over simmering water, place egg yolks and ¼ cup (50 grams) sugar. Cook, whisking frequently, until thickened and ribbon-consistency and an instant-read thermometer registers 158°F (70°C). Remove from heat, and set aside.
  4. In the heatproof bowl of a stand mixer, whisk together egg whites and remaining ½ cup (100 grams) sugar by hand. Place bowl over a saucepan of simmering water. Cook, whisking frequently, until an instant-read thermometer registers 120°F (49°C) to 130°F (54°C).
  5. Carefully return bowl to stand mixer. Using the whisk attachment, beat at medium-high speed until stiff peaks form.
  6. Using a balloon whisk, fold egg white mixture into egg yolk mixture in three additions alternately with chocolate mixture, beginning and ending with egg white mixture. Fold in whipped cream in two additions. Use immediately.

Chocolate Mirror Glaze
 
Makes 2⅓ cups
Ingredients
  • ¼ cup (60 grams) cold water
  • 1 (0.25-ounce) envelope (7 grams) unflavored gelatin
  • 1½ cups (300 grams) granulated sugar
  • ¾ cup (180 grams) heavy whipping cream
  • ¼ cup (60 grams) water
  • 1¼ cups (106 grams) Dutch process cocoa powder, sifted
Instructions
  1. In a small bowl, place ¼ cup (60 grams) cold water. Sprinkle gelatin over water, and let stand until dissolved.
  2. In a tall-sided medium saucepan, heat sugar, cream, and ¼ cup (60 grams) water over medium heat, stirring constantly, until sugar dissolves and mixture starts to boil. Cook, without stirring, until an instant-read thermometer registers 215°F (102°C) to 220°F (104°C). (This will happen quickly and mixture will bubble up, so make sure you use the correct pan.) Remove from heat, and whisk in gelatin mixture and cocoa. Pour mixture through a fine-mesh sieve into a heatproof bowl, and let cool until instant-read thermometer registers 105°F (41°C) before using. (Temperature is key for this to work correctly. Do not let it get too cold or it will set too fast and will not coat completely, and if you use it too hot, it will be super thin on the cake and will melt your mousse.)

 

Making and Baking the Cake

Though the cake batter may appear thin, this chocolate cake bakes up beautifully tender and moist and serves as the perfect base to our Triple-Chocolate Mousse Cake

1. Preheat oven to 325°F (170°C). Spray 2 (8-inch) round cake pans with baking spray with flour. 

2. In a large bowl, whisk together flour, baking powder, and salt.

                                                                     

3. In a medium bowl, whisk together hot coffee and cocoa until smooth. Whisk in milk. Add brown sugar, oil, egg, and vanilla, and whisk until combined. Gradually add flour mixture, whisking just until combined. Divide batter between prepared pans (about 300 grams each). (Batter will be thin.) With this cake, evenness is everything. That’s why we recommend weighing the cake batter for this one; if the cakes are not even, you will be able to tell when you cut the cake.

4. Bake until cake pulls away from sides of pan and a wooden pick inserted in center comes out clean, about 15 minutes. Let cool completely in pan.

5. Level cooled cake layers, if desired. Place 1 cake layer in center on base of a 9-inch springform pan without sides. It’s very important that you place the cake layer in the center of the base of the springform so you have an even layer of the mousse on the outside of the cake.

 

Making Your Filling and Mousse

From creating the cake’s creamy and sweet White Chocolate Filling to whipping up eggs and cream for the cake’s fluffy outer layer of mousse, we show you every step in creating the inner components of this cake

Fixing Up the Filling

                                                                 

1. In the bowl of a stand mixer fitted with the paddle attachment, beat cream cheese at medium speed until smooth, about 1 minute. Add sugar, and beat at medium-low speed until sugar is melted and mixture is smooth, stopping to scrape sides of bowl. Add melted white chocolate, and beat until well combined. The temperature of the white chocolate is very important; too hot and it will melt your cream cheese down, too cold and it will turn into clumps when you add it in. With mixer on medium-low speed, add cold cream in a slow, steady stream. Thoroughly scrape sides of bowl. Slowly increase mixer speed to medium, beating until stiff peaks form, about 1 minute. 

 

Making the Mousse

              

1. In the bowl of a stand mixer fitted with the whisk attachment, beat cold cream and vanilla, slowly increasing mixer speed to medium-high, until stiff peaks form, about 2 minutes. Transfer to a medium bowl; cover and refrigerate until ready to use. Clean bowl of stand mixer and whisk. 

              

2. In the top of a double boiler, place chocolate and butter. Cook over simmering water, stirring occasionally, until melted and smooth. Let stand until ready to use.

                                                                

3. In a large heatproof bowl over simmering water, place egg yolks and ¼ cup (50 grams) sugar. Cook, whisking frequently, until thickened and ribbon-consistency and an instant-read thermometer registers 158°F (70°C). Remove from heat, and set aside.

                                                           

4. In the heatproof bowl of a stand mixer, whisk together egg whites and remaining ½ cup (100 grams) sugar by hand. Place bowl over a saucepan of simmering water. Cook, whisking frequently, until an instant-read thermometer registers 120°F (49°C) to 130°F (54°C). This step helps the sugar dissolve while also cooking the egg whites to ensure safe consumption.

5. Carefully return bowl to stand mixer. Using the whisk attachment, beat at medium-high speed until stiff peaks form.

               

6. Using a balloon whisk, fold egg white mixture into egg yolk mixture in three additions alternately with chocolate mixture, beginning and ending with egg white mixture. Fold in whipped cream in two additions. Use immediately. With mousse, you want to keep as much of the air in the egg whites and whipped cream as you can. For that reason, it’s important to fold in both very gently and just until combined and a uniform consistency.

 

Assembling the Cake

Now that the filling and mousse are made, it’s time to assemble

              

1. Place White Chocolate Filling in a large pastry bag, and cut a 1-inch opening in tip. Pipe an even layer on top of cake layer in pan, smoothing with an offset spatula. Top with remaining cake layer. (Make sure filling is smooth and does not stick out past sides of cake.) Place sides on springform pan; cover and refrigerate while preparing mousse. 

                                                                  

2. Place Chocolate Mousse in a large pastry bag, in batches as needed, and cut a 1-inch opening in tip. Pipe around outside edges and on top of cake, smoothing with an offset spatula. (Springform pan will be full and mousse will come to the top). Cover and freeze until firm, about 4 hours or up to overnight.

 

Setting Up for Success

There are many components at play when creating a successfully shiny mirror glaze. Here, we list three of the main requirements to ensure your mirror glaze comes out perfectly.

Requirement 1: A Smooth Surface

  • Like trees reflecting on the smooth surface of a lake, your mirror glaze will only become shiny and reflective if it’s poured onto a similarly smooth surface. If the surface of your cake is uneven, you risk the glaze pooling in places or not spreading out properly, ruining its smooth, reflective effect.

Requirement 2: No Air Bubbles

  • It’s important not to incorporate excess air into your mirror glaze, so when you’re whisking in the gelatin mixture and cocoa, whisk just until combined. After going through the sieve, there shouldn’t be any air bubbles in the mixture.
  • It’s also important to limit the number of air bubbles on the surface of the cake that you’ll be pouring the glaze onto. Smoothing the surface with a warmed offset spatula is the simplest way to get rid of any air bubbles on the surface of the mousse.

Requirement 3: Proper Temperatures

  • For mirror glaze to work, every element must be the proper temperature. The glaze needs to cool to 105°F (41°C) before using or it will be too fluid and won’t set up in time. The cake below also must be cool; otherwise, the mousse could potentially melt into the glaze.

 

Mirror, Mirror 

Perhaps the most temperamental element of this cake, mirror glaze is simple to make but relies upon exact temperatures and timing to achieve its signature glossy shine. For that reason, it’s important to move quickly and efficiently and make sure you have your cake ready to go once the mirror glaze reaches temperature.

1. In a small bowl, place ¼ cup (60 grams) cold water. Sprinkle gelatin over water, and let stand until dissolved. 

              

2. In a tall-sided medium saucepan, heat sugar, cream, and ¼ cup (60 grams) water over medium heat, stirring constantly, until sugar dissolves and mixture starts to boil. Cook, without stirring, until an instant-read thermometer registers 215°F (102°C) to 220°F (104°C). (This will happen quickly and mixture will bubble up, so make sure you use the correct pan.) Remove from heat, and whisk in gelatin mixture and cocoa. Pour mixture through a fine-mesh sieve into a heatproof bowl, and let cool until instant-read thermometer registers 105°F (41°C) before using. (Temperature is key for this to work correctly. Do not let it get too cold or it will set too fast and will not coat completely, and if you use it too hot, it will be super thin on the cake and will melt your mousse.)

 

The Finishing Touch

Now that the Chocolate Mirror Glaze is made, it’s time to let it shine as it enrobes your beautifully constructed Chocolate Mousse Cake

                                                              

1. After preparing the Chocolate Mirror Glaze and as it is cooling, using a small kitchen torch or a hot towel, heat sides of springform pan. This will loosen the sides and prevent the frozen mousse from clinging to the sides. Remove sides of pan, and using a large spatula, transfer cake to a 9-inch cake board. Using a hot, dry spatula, smooth edges and top as needed. Freeze until glaze reaches correct temperature. Keeping your cake cold is essential; otherwise, the mousse might melt under the mirror glaze. 

                                                                

2. Line a rimmed baking sheet with plastic wrap; place a wire rack on top. Place cake on prepared rack. Pour Chocolate Mirror Glaze over cake, making sure sides are completely covered. Using a large spatula, swipe top of cake once to remove any excess glaze. (Do not do this more than once; it will start to set and will not be completely smooth anymore.) Refrigerate until glaze is set and cake has thawed in center, about 3 hours. Serve cold.

 

Previous articleConfetti Ice Cream Cake
Next articleHoney Butter Yeast Rolls

LEAVE A REPLY

Please enter your comment!
Please enter your name here

Rate this recipe:  

This site uses Akismet to reduce spam. Learn how your comment data is processed.