Chocolate Buttercream Cake

By norsegal8

Ingredients

• CAKE:
• 1 3/4 cup cake flour
• 1 cup good cocoa powder
• 1 1/2 teaspoon baking soda
• 1/4 teaspoon salt
• 3/4 cup unsalted butter, at room temperature
• 2/3 cup sugar
• 2/3 cup light brown sugar, packed
• 2 extra large eggs at room temperature
• 2 teaspoons vanilla
• 1 cup buttermilk at room temperature
• 1/2 cup sour cream at room temperature
• 2 tablespoons brewed coffee
• FROSTING:
• 10 ounces bittersweet chocolate
• 8 ounces semisweet chocolate
• 3 extra-large egg whites at room temperature
• 1 cup sugar
• pinch of cream of tartar
• 1/2 teaspoon salt
• 1 pound unsalted butter at room temperature
• 2 teaspoons vanilla
• 2 teaspoons instant espresso powder dissolved in 1 teaspoon water
• 2 tablespoons dark rum (optional)

Preparation

Step 1

Preheat the oven to 350 degrees.

Butter 2 8-inch round cake pans. Line the bottoms with parchment paper, butter the paper and dust the plans with flour, shaking out any excess. In a large bowl, sift together the flour, cocoa, baking soda and salt.

In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar on high speed until light and fluffy, about 5 minutes. Add the eggs and vanilla and mix well. Combine the buttermilk, sour cream and coffee. On low speed add the flour mixture and the buttermilk mixture alternately in thirds, beginning with the flour mixture and ending with the flour mixture. Mix the batter only until blended.

Divide the batter between the 2 pans and smooth the tops with a spatula. Bake on the middle rack of the oven for 25 - 30 minutes, or until a toothpick comes out clean. Cool for 10 minutes, remove from the pans and allow to finish cooling.

FOR THE FROSTING:
Chop the chocolate and melt in a bowl over simmering water until smooth. Allow to cool.

Mix the egg whites, sugar, cream of tartar and salt in the bowl of an electric mixer fitted with the whisk attachment. Heat the 3 egg white in a bowl over simmering water until they are warm to the touch, about 5 minutes. Whisk on high speed for 5 minutes, or until the meringue is cool and holds a stiff peak.

Add the butter, 1 tablespoon at a time, while beating on medium speed. Scrape down the bowl, add the chocolate, vanilla, espresso and rum and mix for 1 minute until the chocolate is completely blended. If the buttercream seems very soft, allow it to cool, then beat it again.

Frost the cake and serve.