Bumpy Cake
Makes 1 (13×9-inch) cake
  • ⅔ cup (150 grams) unsalted butter, softened
  • 1 cup (200 grams) granulated sugar
  • ¾ cup (165 grams) firmly packed dark brown sugar
  • 2 large eggs (100 grams), room temperature
  • 1 teaspoon (4 grams) vanilla extract
  • 2 cups (250 grams) all-purpose flour
  • 1½ teaspoons (7.5 grams) baking soda
  • ½ teaspoon (1.5 grams) kosher salt
  • ½ cup (43 grams) Dutch process cocoa powder
  • ½ cup (120 grams) warm water (105°F/41°C to 110°F/43°C)
  • 1 teaspoon (2 grams) instant espresso powder
  • ¾ cup (180 grams) heavy whipping cream, room temperature
  • ¼ cup (60 grams) sour cream, room temperature
  • Vanilla Buttercream (recipe follows)
  • Fudge Frosting (recipe follows), warmed
  1. Preheat oven to 350°F (180°C). Spray a 13×9-inch baking pan with baking spray with flour. Line pan with parchment paper, letting excess extend over sides.
  2. In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugars at medium speed until fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well after each addition and stopping to scrape sides of bowl. Beat in vanilla.
  3. In a medium bowl, whisk together flour, baking soda, and salt. In another medium bowl, whisk together cocoa, ½ cup (120 grams) warm water, and espresso powder until smooth. Add cream and sour cream, and whisk until combined. With mixer on low speed, gradually add flour mixture to butter mixture alternately with cocoa mixture, beginning and ending with flour mixture, beating just until combined after each addition. Pour into prepared pan.
  4. Bake until cake springs back when lightly pressed in center and edges begin to pull away from pan, 30 to 35 minutes. Let cool completely in pan.
  5. Place Vanilla Buttercream in a pastry bag fitted with a ⅝-inch round piping tip (Ateco #808). Pipe buttercream from center edge of one long side to center of opposite side. Pipe 3 lines, each 1 inch apart, on either side of center line (7 lines total). Freeze until ready to frost.
  6. Slowly pour warm Fudge Frosting over buttercream bumps in long even strokes until evenly distributed. If frosting thickens too much, microwave on high in 15-second intervals, stirring between each, until smooth and pourable. Refrigerate for 30 minutes before serving.
Recipe by Bake from Scratch at https://www.bakefromscratch.com/bumpy-cake/