Mocha Layer Cake

Instructions

• Preheat the oven to 350 degrees F (175 degrees C). Grease and flour three 8-inch round cake pans.
• Dissolve baking soda in buttermilk. Combine flour, cocoa powder, and salt in a separate bowl.
• Beat butter in a mixing bowl until creamy. Gradually add sugar, beating well. Add flour mixture alternately with the buttermilk mixture, beginning and ending with the flour mixture; mix well after each addition. Stir in 1 tablespoon plus 2 teaspoons coffee and vanilla.
• Beat egg whites in a glass, metal, or ceramic bowl until stiff peaks form. Gently fold into the creamed mixture. Pour batter into the prepared cake pans.
• Bake in the preheated oven until a toothpick inserted into the center comes out clean, 30 to 35 minutes. Cool in the pans for 10 minutes. Run a table knife around the edges to loosen. Invert cakes carefully onto a serving plate or cooling rack. Let cool, about 20 more minutes.
• While the cake is cooling, beat butter and cocoa powder for frosting in a bowl until well creamed. Add powdered sugar, egg yolk, and vanilla and beat until smooth.
• Stack the 3 cake layers on top of each other, spreading frosting between layers, and on top of the cake.