You can top a cake with whipped cream or glaze it with ganache, but the most popular way to finish off a cake is with a layer of buttercream frosting. Buttercream is a sweet frosting that is rich with butter and has a silky texture that melts against your tongue when you bite into it. There are several types of buttercream and some are far more common than others.
A simple buttercream, also called an American buttercream, is probably the most common buttercream variation. This frosting is made by creaming together butter, confectioners’ sugar, milk or cream, and some kind of flavorings until everything is smooth and fluffy. This type of frosting is sweet, easy to work with and keeps very well, all of which make it a very popular choice with cake bakers. The other common type of buttercream is a meringue-based buttercream. With this type of frosting, either Italian meringue (hot sugar beaten into egg whites) or Swiss Meringue (egg whites and sugar heated together and beaten) is prepared and cooled, then a generous amount of butter is beaten into it until the frosting is glossy. These types of buttercreams have a much lighter texture than a simple buttercream and they have a much more distinct butter flavor to them.
Less well known buttercreams include a French buttercream, which is prepared in a similar way to the meringue buttercreams but uses egg yolks that are beaten until very light instead of egg whites. This type of buttercream tends to be the trickiest to make. There are also custard based buttercreams, where a flavored pastry cream has butter beaten into it to form a rich, thick buttercream typically used for filling cakes rather than frosting them. These additional buttercreams are also excellent examples of how easy it is to experiment and use other ingredients – peanut butter or nutella, for instance – to make your own twist on buttercream that you can use to frost your favorite cake or cupcake recipes.