What is a cupcake without buttercream frosting? A Muffin! Buttercream or frosting is the thick, fluffy mixture that is used to decorate our cakes and cupcakes. It is the stuff that holds its shape on your cakes and cupcakes and looks pretty in various piped designs. The most popular flavour is vanilla to which oil-based food colour can be added to match any colour scheme, it can be made whiter or even black, and any colour in between. Chocolate is the next favourite, which is a rich dark brown, perfect for chocolate cakes and cupcakes, both are ready to use straight from the pot.