Buttercream (also known as butter cream or butter icing) is a type of icing used inside cakes, as a coating, and as decoration. In its simplest form, it is made by creaming butter with powdered sugar, although other fats can be used, such as margarine or lard. 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. Simple buttercream, also known as American buttercream, is made by creaming together fat and powdered sugar (also known as "icing sugar" or "confectioner's" sugar) to the desired consistency and lightness. Small quantities of whole eggs, egg whites, egg yolks, or milk may be included. Some recipes also call for non-fat milk solids. Due to a high sugar content, the frosting can form a thin crust, which prevents sticking. Sometimes called Rose Paste, this buttercream is creamed much less than a regular simple buttercream resulting in a stiff paste suitable for making flowers and other cake decorations. It is usually the sweetest of all the buttercream. Also known as Italian buttercream, this buttercream is similar in preparation to a French buttercream. A boiling syrup of sugar and water cooked to soft-ball stage is poured over beaten egg whites to create a meringue. The sugar syrup essentially cooks the egg whites, eliminating most health concerns. Fat is added to the meringue as it cools. Frequently, when adding in the butter or shortening, the mixture will separate and look "curdled". Extensive mixing is needed to incorporate the ingredients. This is the most commonly used frosting for bakery cakes, and it does not form a crust.

Alternatively the sugar can be added directly to cold egg whites in a bowl over a simmering water bath. The mixture is whipped until the temperature of the mix reaches 140 F. At this point the egg is safely pasteurized. The mixture is then whipped at high speed until it forms stiff peaks and has cooled. Butter is added with a small amount of margarine to stabilize the cream. This is known as a Swiss buttercream. French buttercreams are made by beating a sugar syrup which has reached the soft-ball stage into beaten egg yolks and whipping to a light foam. Softened butter is then whipped in. This icing is very rich, smooth, and light. French buttercreams tend to melt faster than other buttercreams due to the high content of fat from the egg yolks and butter. Pastry cream types, sometimes referred to as German buttercreams, are made by beating together thick pastry cream and softened butter, and may be additionally sweetened with extra confectioners' sugar. Similarly, a light custard can be made and beaten with butter. Fondant buttercream is made by creaming together equal parts fondant and butter.