Divide batter between prepared pans, spread evenly. Bake about 30 minutes or until toothpick inserted near centers comes out clean. Cool in pans on wire rack 10 minutes. Remove cakes from pans. Let cool on wire rack. To assemble, place first cake layer on a serving plate. Spread 1-1/2 cups frosting over the top of the layer. Top frosted first layer with second cake layer, top side up. Frost top and sides of entire cake with remaining Chocolate Butter Frosting.