Queque Nego

For the sour cream chocolate cake:

2 cups unbleached all-purpose flour
2 cups granulated white sugar
1 1/4 tsp baking powder
1 tsp salt
1/2 tsp baking soda
2 eggs, at room temperature
4 oz unsweetened chocolate melted (3/4 cup)
1 cup sour cream, at room temp.
3/4 cup milk
1/4 cup unsalted butter
2 tsp vanilla

Place flour, sugar, eggs, chocolate, sour cream, milk, butter and vanilla in the mixer bowl. Attach the flat beater and mixer bowl to the mixer. Set to Stir and mix for 30 seconds. Increase to speed 4 and beat for 2 minutes, stopping twice to scrape down sides.

Divide batter between prepared pans and smooth tops. Bake in middle of preheated oven for 25 to 30 min. or until a tester inserted in the center comes out clean and edges of cake begin to pull away from sides of pans. Let cool in pans or wire racks for 5 min. then invert onto racks, peel off paper and let cool completely.
Chocolate Buttercream Filling

2 egg yolks
1 cup powdered sugar
2 squares (2 ounzes) semisweet chocolate, melted
3/4 cup (1 1/2 sticks) butter, softened
1/2 teaspoon vanilla

Place egg yolks in bowl of electric stand mixer. Turn to medium-high and whip 2 min. Stop and scrape bowl.
Reduce speed to medium and gradually add powdered sugar, chocolate, butter, and vanilla. continue beating until fluffy, about 5 minutes.