Does it look complicated? It doesn't have to be! With a Layer Cake Set, it's easy to make a rainbow-coloured cake with multiple layers. METHOD: Mix the cake batter and divide it up into as many colours as you want. Use gel food colouring to dye each portion, then pour the batter into the cake pans. Bake in the oven, loosen from the pans and assemble. Use a cake spatula and cover the cake with whipped cream or buttercream; pipe it on and finish with sprinkles. TIP! Use our plastic film, which is specially intended for assembling cakes. It will make it easier to create an even edge as you spread filling between the various layers.