The following is a moist and chocolaty cake suitable for many occasions. Use it to form the base for Tepee Birthday Cakes.
Makes one 9-inch round double layer cake.
Make cake layers:
Preheat oven to 350°F. Grease and flour two 9-inch round cake pans, knocking out excess flour.
Into a bowl sift together flour, cocoa powder, baking powder, baking soda, and salt. In a small bowl whisk together sour cream, water, and vanilla.
In a large bowl with an electric mixer beat together butter and sugar until light and fluffy. Beat in eggs, 1 at a time, beating well after each addition. Add flour mixture to butter mixture in batches alternately with sour cream mixture, beginning and ending with flour mixture and beating until batter is blended well.
Divide batter between prepared pans and smooth tops. Bake layers in middle of oven 25 to 30 minutes, or until a tester comes out clean. Cool cake layers in pans on racks 10 minutes before turning out onto racks to cool completely. Cake layers may be made 1 week ahead and frozen, wrapped well in plastic wrap. Thaw layers before proceeding with recipe.
In a bowl with an electric mixer beat together butter and cream cheese until light and fluffy. Add remaining ingredients and beat until combined well.
Arrange 1 cake layer on a large plate and spread with about 3/4 cup frosting. Top frosting with remaining cake layer. If making tepee birthday cakes, stop here and reserve remaining frosting. If making conventional layer cake, spread top and side of cake with remaining frosting.