Make up the cake mix according to manufacturer's instructions. Measure out 3 pounds batter, deposit 1 pound 8oz into a sprayed and papered 8-inch cake pan. Repeat again to make 2 cakes total. Bake at 350F until cake springs back lightly when touched. Let cool completely. Once cooled, trim the bellies of each cake, saving them for other uses. Place one cake round on a cake board, and fill with chocolate VelveTop. Place the other round on top and crumb coat with chocolate VelveTop. Using a variety of sizes and styles of star tips, load bags with chocolate VelveTop and decorate the cake with different sizes of rosettes.