Buttercream is a type of icing or filling, used inside cakes, as a coating, and as decoration. Buttercream is made by creaming butter with powdered sugar to the desired consistency and lightness. Small quantities of whole eggs, egg whites, egg yolks, or milk may be included. Colorings and flavorings are often added, such as cocoa powder or vanilla extract. Buttercreams are a popular topping for cupcakes, sponge cakes, butter cakes and other desserts.