Baking School In-Depth: Egg Custard Tarts

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egg custart tarts baking school in-depth

Baking School In-Depth is going global this year with a brand-new lineup of recipes from around the world. To kick off the New Year, we begin our baking adventure in China with Egg Custard Tarts, or dan tat! Despite their prominence in Lunar New Year celebrations, egg tarts can be found year-round at Chinese bakeries and dim sum restaurants. With a gorgeously golden and velvety custard filling and a crisp yet tender crust, these shareable sweets are an excellent introduction to Chinese baking. In China, there are actually two kinds of egg tarts commonly found: Hong Kong-style, which trace their roots back to Canton (now Guangzhou), like these, and Macau-style, which more closely resemble pastéis de nata, a Portuguese version of the egg tart that often includes spices like cinnamon in the filling, a caramelized top layer, and a shatteringly crisp puff pastry shell. (Macau was under Portuguese rule for more than 400 years, not returning to Chinese sovereignty until 1999, hence the Portuguese influence.) Hong Kong-style egg tarts are said to incorporate some influence from those same Portuguese settlers, but mainly from English custard tarts. They became a staple of afternoon tea around the 1920s due to the influx of British businessmen to the area, and after World War II, a version appeared in Hong Kong that was then perfected to become the egg tarts we know today. In this month’s module, we make those perfect egg tarts more accessible than ever. From making a pâte sucrée-style crust to preparing the filling and ensuring a smooth, glossy finish with no cracks, we break down each and every step in the process.

Click here to download a printable PDF of this lesson, or keep scrolling to view our digital lesson. And be sure to join us for Baking School with Williams Sonoma on Monday, January 9, 2023, at 5 p.m. PT. Brian Hart Hoffman will be joined by Kristina Cho to make these fun and festive tarts; this is one baking celebration you won’t want to miss!

Ingredient Breakdown

Great recipes require great ingredients. This combination of simple ingredients is key to creating exceptional Egg Custard Tarts.

Unsalted butter: Because butter is key to the texture and richness of the crust, choosing a European-style butter, which has a higher fat ratio than generic grocery store butter, will yield the best results. As for unsalted versus salted, —salt content can vary across different brands of butter, so we use unsalted butter, which allows us to add the exact amount of kosher salt desired.

Confectioners’ sugar: To achieve a tender, melt-in-your-mouth texture, our tart crusts use confectioners’ sugar instead of granulated sugar. Confectioners’ sugar also helps create a stronger, sturdier crumb so each tart will hold its shape even after being removed from its pan. With this crust, we’re not looking for a dramatic rise or lift in the oven, so creaming butter and granulated sugar to create air pockets is not essential. Instead, confectioners’ sugar is beaten with the butter and salt until creamy to create a smooth, uniform dough.

Kosher salt: Salt is an all-encompassing flavor booster, and sweet bakes without salt tend to taste flat. We like kosher salt because it’s a pure, additive-free salt that has a crisp, clean taste. Plus, it’s flaked rather than granulated, which allows for more even distribution in both our dough and filling.

Egg yolks: Responsible for adding richness to both the crust and the filling of our egg tarts, egg yolks are an essential ingredient in this recipe. In the crust, they help bind and enrich the dough. In the custardy filling, their magic is molecular. Egg yolks are full of proteins and fats, and coagulation, the change in the structure of protein (from a liquid form to solid or a thicker liquid), is brought about through heat. The egg yolks in the filling are also the key to the rich golden-yellow color of the filling.

Vanilla extract: Vanilla adds incredible depth of flavor without being overpowering. A dash of high-quality vanilla extract gives baked treats a multidimensional updo.

All-purpose flour: For a delicate crumb, a special flour that balances between soft and hard is needed. All-purpose wheat flour has a protein content of 10% to 12%, so the crust of our tarts is tender but has enough gluten structure to hold together. The biggest mistake you can make with tart and pie dough is overmixing, because the more the gluten is activated, the tougher it will be.

Unbleached cake flour: Cake flour, unlike all-purpose, is lower in protein and creates softer, more-delicate bakes. So, when used in combination with all-purpose flour, you get a slightly lighter crumb that still has a satisfying bite to it. Unlike bleached flour, which is treated with bleaching agents to speed up the flour’s aging process, resulting in a whiter, finer-grain flour with a softer texture, unbleached flour bleaches naturally as it ages, making it denser in consistency and less white. The density provides more structure in baked goods, making it perfect for our egg tart shells.

Water: When combined with the evaporated milk in this recipe, water adds necessary moisture without sacrificing or inhibiting the rich flavor of the eggs in the custard filling. In a sense, you’re re-adding some of water that’s cooked out when evaporated milk is made but without reducing the concentration enough to create regular milk.

Granulated sugar: These egg tarts are not meant to be overly sweet, hence the seemingly minimal amount of sugar added to the filling. However, with too much sugar in the filling, it becomes more prone to browning and caramelization. The touch of sugar also helps prevent the custard from curdling, slowing the coagulation of the eggs. So, though it may seem like a minimal addition, the sugar in this recipe is doing so much more than just adding sweetness.

Evaporated milk: Evaporated milk is made from fresh milk from which 60% of the water has been removed through evaporation under high pressure and temperatures. After the water has been removed, the milk is chilled, stabilized, and sterilized. The high heat under which the milk is processed creates a slightly caramelized flavor thanks to the Maillard reaction that occurs and contributes to the milk’s slightly off-white color.

Tool Talk

The tools behind our technique

Bench scraper: Whether you’re looking for an easy way to lift and transfer your dough, a simple tool that can expertly cut and divide doughs, or a way to clear your work surface, the bench scraper is your new best friend. (Pictured is the Williams Sonoma Olivewood Bench Scraper.)

Kitchen scale and liquid-measuring cup: When used in combination, these two tools will yield the most accurate measurements. Our bakes look best when they’re uniform in size, shape, and color, and this winning combination will help ensure identical tarts every time. (Pictured are the Zwilling Digital Scale and OXO 4-Cup Angled Measuring Cup.)

Medium saucepan: To heat the filling for these tarts, you want a stainless steel saucepan that’ll heat efficiently and uniformly with precise temperature control and no hot spots. This will help prevent burning or scalding. (Pictured is the Williams Sonoma Signature Thermo-Clad™ Stainless-Steel Saucepan.)

Mini tart pans: These little pans give our tarts their signature shape. The pans are not nonstick, so it’s important that you spray them before pressing in your crust. Then, after baking, the tarts will be a breeze to pop out and enjoy. (Pictured are Fat Daddio’s 2.5″ Mini Tartlet Pans.)

Baking sheet: A baking sheet placed below your tart pans helps to ensure even heat distribution while also making transferring your tarts to and from the oven a lot easier. (Pictured is the Williams Sonoma Goldtouch® Pro Nonstick Non Corrugated Quarter Sheet.)

Spatula, whisk, and glass bowls: For all your mixing needs, you really can’t beat the basics. Spatulas are perfect for simple stirring and folding; whisks are essential for mixing dry ingredients, whisking eggs, and breaking up clumps; and glass bowls give you a 360-degree visual while staying cool (glass doesn’t conduct heat well). (Pictured are the Williams Sonoma Stainless-Steel Ultimate Silicone SpatulaWilliams Sonoma Prep Tools Stainless-Steel Whisk, and Glass Mixing Bowls.)

Stand mixer: An excellent time- and strength-saver, stand mixers are fantastic at bringing dough together without the effort of hand mixing. But it’s important that your dough’s time in the mixer is short and sparing once the dry ingredients have been added. (Pictured is the KitchenAid® Artisan Stand Mixer, 5-Qt., and KitchenAid® Stand Mixer Clear Glass Bowl Attachment, 5-Qt.)

Fine-mesh sieve: For the perfect, silky smooth egg filling, we use a fine-mesh sieve to separate out any solids that might’ve formed as the filling was mixed. (Pictured is the All-Clad 3-Piece Stainless-Steel Strainer Set.)

Thermometer: An instant-read thermometer is the ultimate tool to check for doneness. As soon as the center of your tarts registers at least 175°F (79°C), they’re done! (Pictured is the OXO Thermocouple Thermometer.)

Egg Custard Tarts

Egg Custard Tarts

We kept our egg tarts simple and classic, combining a buttery, tender pâte sucrée crust and gorgeous, glossy custard filling rich with notes of vanilla and sweet eggy flavor. They’re delicate and rich all at the same time, and simply irresistible. Whether made for Lunar New Year on January 22, or enjoyed later in the year, they’re a staple of Chinese bakeries for a reason.

Egg Custard Tarts
 
Makes 8 mini tarts
Ingredients
  • ⅓ cup (76 grams) unsalted butter, softened
  • ¼ cup (30 grams) confectioners’ sugar
  • ½ teaspoon kosher salt, divided
  • 4 large egg yolks (75 grams), room temperature and divided
  • ¾ teaspoon (3 grams) vanilla extract, divided
  • 1 cup (125 grams) all-purpose flour
  • ¼ cup (31 grams) unbleached cake flour
  • ¼ cup (60 grams) water
  • 2½ tablespoons (30 grams) granulated sugar
  • 2½ tablespoons (37.5 grams) evaporated milk
Instructions
  1. In the bowl of a stand mixer fitted with the paddle attachment, beat butter, confectioners’ sugar, and ¼ teaspoon salt at medium speed until creamy, 1 to 2 minutes, stopping to scrape sides of bowl. Add 1 egg yolk (19 grams); beat until well combined. Beat in ¼ teaspoon (1 gram) vanilla.
  2. In a medium bowl, whisk together flours. With mixer on low speed, gradually add flour mixture to butter mixture, beating just until a dough forms.
  3. Spray 8 (2½x-9/10inch) fluted round tart pans with baking spray with flour; place on a rimmed baking sheet.
  4. Divide dough into 8 portions (about 35 grams each), and shape into balls. Press 1 dough ball into bottom and up sides of 1 prepared tart pan; trim any excess dough. Repeat with remaining dough and remaining tart pans.
  5. In another medium bowl, whisk together remaining 3 egg yolks (56 grams).
  6. In a small saucepan, combine ¼ cup (60 grams) water, granulated sugar, evaporated milk, remaining ½ teaspoon (2 grams) vanilla, and remaining ¼ teaspoon salt. Cook over medium heat until steaming and sugar dissolves. Gradually whisk sugar mixture into egg yolks until well combined.
  7. Position oven rack in bottom third of oven. Preheat oven to 400°F (200°C).
  8. Place a fine-mesh sieve over a large liquid-measuring cup or wide-mouthed pitcher. Strain egg yolk mixture through prepared sieve; discard any solids. Divide strained mixture among prepared crusts (about 18 grams each).
  9. Bake until crust is lightly browned, 10 to 12 minutes, rotating pan halfway through baking. Reduce oven temperature to 350°F (180°C), and bake just until edges of filling start to puff, about 5 minutes more. With oven still on, open oven door about 2 inches; bake until filling is set, a wooden pick inserted in center stands up straight, and an instant-read thermometer inserted in center registers at least 175°F (79°C), 5 to 7 minutes more. Let cool in pans for 15 minutes. Remove from pans, and serve warm or at room temperature.

 

Preparing the Crust

Sitting somewhere between piecrust and shortbread, pâte sucrée serves as the ultimate base for our egg tarts, providing necessary structure without sacrificing texture or flavor. The biggest mistake you can make here is overmixing once the flour has been added, so be sure to beat the mixture just until a dough forms.

                               

1. In the bowl of a stand mixer fitted with the paddle attachment, beat butter, confectioners’ sugar, and ¼ teaspoon salt at medium speed until creamy, 1 to 2 minutes, stopping to scrape sides of bowl. Add 1 egg yolk (19 grams); beat until well combined. Beat in ¼ teaspoon (1 gram) vanilla. 

                             

2. In a medium bowl, whisk together flours. With mixer on low speed, gradually add flour mixture to butter mixture, beating just until a dough forms. Do not overmix at this stage; otherwise, gluten structures will begin to form, creating a tough crust.

3. Spray 8 (2½x9/10-inch) fluted round tart pans with baking spray with flour; place on a rimmed baking sheet.

                

4. Divide dough into 8 portions (about 35 grams each), and shape into balls. Press 1 dough ball into bottom and up sides of 1 prepared tart pan; trim any excess dough. As you’re pressing the dough in, be sure to apply firm but even pressure, getting as close to uniform thickness on the bottom and sides of the tart pan as possible. Although weighing out the dough might feel tedious, it will help to ensure that the tarts are uniform, allowing each to bake evenly. Repeat with remaining dough and remaining tart pans.

 

Making the Filling & Assembling the Tarts

Though eggs can be temperamental with heat, our method of slowly incorporating the warm ingredients into the egg yolks of our custardy filling helps to ensure that curdling won’t occur

1. In another medium bowl, whisk together remaining 3 egg yolks (56 grams). 

                               

2. In a small saucepan, combine ¼ cup (60 grams) water, granulated sugar, evaporated milk, remaining ½ teaspoon (2 grams) vanilla, and remaining ¼ teaspoon salt. Cook over medium heat until steaming and sugar dissolves. Gradually whisk sugar mixture into egg yolks until well combined. In this step, the slower you can add the sugar mixture to the eggs, the better. This way, the eggs can slowly come up to temperature without the shock of a hot liquid all being added at once. Added too quickly or without constant stirring, the risk of your eggs curdling greatly increases.

3. Position oven rack in bottom third of oven. Preheat oven to 400°F (200°C).

                                               

4. Place a fine-mesh sieve over a large liquid-measuring cup or wide-mouthed pitcher. Strain egg yolk mixture through prepared sieve; discard any solids. Divide strained mixture among prepared crusts (about 18 grams each). To gently get rid of any bubbles that might form on the surface of your tarts, you can run a kitchen torch over the tops of each tart to help make the bubbles dissipate.

5. Bake until crust is lightly browned, 10 to 12 minutes, rotating pan halfway through baking. Reduce oven temperature to 350°F (180°C), and bake just until edges of filling start to puff, about 5 minutes more. With oven still on, open oven door about 2 inches; bake until filling is set, a wooden pick inserted in center stands up straight, and an instant-read thermometer inserted in center registers at least 175°F (79°C), 5 to 7 minutes more. Let cool in pans for 15 minutes. Remove from pans, and serve warm or at room temperature.

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