The Best Chocolate Cake With Egg Yolk Buttercream

• cake
• cups all-purpose flour, plus more for pans↗1 3⁄4
• cups sugar↗2
• cup cocoa powder↗3⁄4
• teaspoons baking soda↗2
• teaspoon baking powder↗1
• teaspoon kosher salt↗1
• cup buttermilk, shaken↗1
• cup vegetable oil↗1⁄2
• extra-large eggs, at room temperature2
• teaspoon pure vanilla extract↗1
• cup hot coffee1
• frosting↗
• ounces semisweet chocolate (recommended ( Callebaut)↗6
• lb unsalted butter, at room temperature↗1⁄2
• extra-large egg yolk, at room temperature1
• teaspoon pure vanilla extract↗1
• cups powdered sugar, sifted↗1 1⁄4
• tablespoon instant coffee powder↗1

Step-by-step instructions

1. 1

   Preheat the oven to 350 degrees F. Butter 2 (8-inch) round cake pans. Line with parchment paper, then butter and flour the pans.

2. 2

   Sift the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with a paddle attachment and mix on low speed until combined. In another bowl, combine the buttermilk, oil, eggs, and vanilla. With the mixer on low speed, slowly add the wet ingredients to the dry. With mixer still on low, add the coffee and stir just to combine, scraping the bottom of the bowl with a rubber spatula. Pour the batter into the prepared pans and bake for 35 to 40 minutes, until a cake tester comes out clean. Cool in the pans for 30 minutes, then turn them out onto a cooling rack and cool completely.

3. 3

   Place 1 layer, flat side up, on a flat plate or cake pedestal. With a knife or offset spatula, spread the top with frosting. Place the second layer on top, rounded side up, and spread the frosting evenly on the top and sides of the cake.