Ingredients
- Cake:
- 1/2 c natural cocoa powder
- 1/2 c boiling water
- 2 1/4 c sifted all purpose flour
- 1 1/2 tsp baking soda
- 1/4 tsp salt
- 3/4 c unsalted butter at room temperature
- 1 3/4 c sugar
- 1 tsp pure vanilla extract
- 2 large eggs
- 1 1/3 c sour cream
- Frosting:
- 6 oz. semisweet chocolate, chopped
- 2 tbsp water
- 1/2 c sugar
- 4 large egg yolks
- 3/4 tsp pure vanilla extract
- 1 c unsalted butter cut into 16 pieces, at room temperature
Preparation
Step 1
Position a rack in the middle of the oven and preheat the oven to 350 degrees F. Butter and flour two 9 x 2" round cake pans.
To make the cake, whisk together the cocoa and boiling water in a small bowl until smooth. Whisk together the flour, baking soda and salt in a medium bowl.
Beat the butter, sugar and vanilla with an electric mixer on medium speed in a large bowl until well blended; the mixture will be dry. Add the eggs one at a time, beating well after each addition. Reduce the speed to low and beat in the flour mixture alternately with the sour cream, beginning and ending with the flour, just until well blended. Add the cocoa mixture and blend well. Divide the batter evenly between the prepared pans.
Bake for 40 minutes, or until a wooden pick inserted near the center comes out clean. Cool the cakes in the pans on wire racks for 20 minutes, then invert the cakes onto the racks and remove the pans. Turn the cakes right side up and cool completely.
To make the frosting, melt the chocolate with the water in a small heatproof bowl over a double boiler.
Heat the sugar with the egg yolks in another heatproof bowl over double boiler, whisking constantly for about 4 minutes until the sugar is dissolved and the mixture is warm to the touch. Whisk the sugar mixture into the chocolate mixture, add the vanilla and beat well in mixer on high for 3 minutes or until the mixture has cooled to room temperature. Beat in the butter one piece at a time, beating until smooth after each addition.
To assemble the cake, place 1 cake layer on a serving plate. Spread about 1 c frosting evenly over the layer. Top with the remaining cake layer and frost with the remaining frosting.
Serve by cutting into wedges.