Make a three-dimensional top hat cake for a unique party treat. The cake is made from a large, round base cake and stacks of smaller round cakes, which are all covered in a smooth coating of buttercream icing. Make that top hat cake black for a traditional-looking hat, or make a cake that coordinates with your theme, from a green St. Patrick's Day hat to a red, white and blue top hat to celebrate Independence Day.
Prepare two store-bought cake mixes according to the package instructions. Pour the batter into the cake pans. Bake the cakes according to package instructions and cool for 20 minutes in the pans.
Remove the cakes from the pans and continue to cool the cakes thoroughly at room temperature.
Pour a little bit of black powder food coloring into the icing and mix. Keep adding small amounts of the powder until the icing is black. Start with a chocolate buttercream icing and you will require less powder than with a white icing.
Spread a moderately thin coating of icing over the top and sides of each cake and then cool the iced cakes in the refrigerator for at least half an hour.
Spread a filler icing on the bottom of one of the 6-inch cakes and place it in the center of the larger cake. Spread the filler icing on top of it, and also on the top of one more 6-inch cake. Stack the cakes to make the top hat shape.
Use a smooth icing spatula to apply a thick, even coating of black icing over the entire top hat.
Spread a layer of clear icing gel evenly around the bottom of the stack of 6-inch cakes to make the band around the top hat.