Cocoa Layer Cake

yield: Makes 10 servings

active time: 1 hour

total time: 3 hours (includes chilling time)

ingredients: 1/2 cup natural unsweetened cocoa powder (spooned into cup to measure, then leveled) 1 cup luke warm water, divided

Ingredients:

1/2 cup buttermilk

1 1/2 cups cake flour (spooned into cups to measure, then leveled)

3/4 teaspoon baking soda

1 cup sugar

1/2 cup (packed) golden brown sugar

1/2 cup (1 stick) unsalted butter, room temperature

2 large eggs, room temperature, beaten to blend

Frosting:

10 tablespoons (1 1/4 sticks) unsalted butter

1 1/3 cups (packed) golden brown sugar

1 cup natural unsweetened cocoa powder

2 teaspoons instant espresso powder

1 cup heavy whipping cream

2 teaspoons vanilla extract

Special equipment: 3 9-inch-diameter cake pans with 1 1/2-inch-high sides

preparation:

For cake:
Position 1 rack in top third and 1 rack in bottom third of oven; preheat to 350°F. Butter three 9-inch-diameter cake pans with 1 1/2-inch-high sides. Line with parchment paper rounds; butter parchment. Whisk cocoa and 1/2 cup warm water in small bowl. Whisk buttermilk and 1/2 cup water in another small bowl. Sift flour, baking soda, and 1/4 teaspoon salt into medium bowl. Using electric mixer, beat both sugars and butter in large bowl until pale yellow and fluffy (mixture will appear granular), about 5 minutes. With mixer running, gradually add beaten eggs, then beat until smooth and fluffy, about 15 seconds. Add cocoa mixture; beat to blend. Add flour mixture in 3 additions alternately with buttermilk mixture in 2 additions, beating to blend after each addition. Divide batter among pans (about 1 3/4 cups each).

Bake cakes until tester inserted into center comes out clean, reversing pans halfway through baking, about 18 minutes. Cool completely in pans on racks.

For frosting:
Melt butter in medium saucepan over medium heat. Stir in sugar, cocoa, espresso powder, and 1/2 teaspoon (scant) salt. Gradually stir in cream. Stir until mixture is very hot and just begins to simmer at edges. Reduce heat to low; stir 1 minute to let flavors blend. Transfer to medium bowl; stir in vanilla (frosting will resemble chocolate sauce). Chill until just thickened, stirring occasionally, about 1 1/2 hours. Let stand at room temperature.

Run knife around cake sides. Carefully invert 1 cake onto plate (cake is very tender); peel off parchment. Spread with 1/2 cup frosting. Invert second cake onto palm of hand. Position cake 2 inches above frosted cake layer. Carefully slide cake onto first cake layer. Peel off parchment. Spread cake with 1⁄2 cup frosting. Repeat with third cake layer. Spread remaining frosting over top and sides of cake. DO AHEAD: Can be made 1 day ahead. Cover with cake dome; let stand at room temperature.

Cut into wedges and serve.