Combine all ingredients except Sour Cream-Chocolate Frosting in a large mixing bowl; beat 4 minutes at medium speed of an electric mixer. Pour batter into 2 greased and floured 23 cm round cakepans. Bake at 160ºC or 35 minutes or until a wooden pick inserted in center comes out clean. Cool in pans 10 minutes; remove from pans, and let cool completely on wire racks. Spread Sour Cream-Chocolate Frosting between layers and on top and sides of cake. ----