Simple buttercream
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.
Decorator's buttercream
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 buttercreams.
Meringue-type 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 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-type buttercream
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-type buttercream
Choice of Fat
The choice of fat in a buttercream frosting relates closely to the stability. Often, some amount of vegetable shortening is combined with butter for better consistency and resistance to heat.
Butter
Sweet cream unsalted butter is traditionally the fat of choice for buttercreams, as evidenced by the name. Butter provides a more delicate texture and superior flavor and mouthfeel (texture) when compared to vegetable shortening. Butter melts at a lower temperature, though, making it more difficult to use. The coloring provided by the butter is slightly off-white in the final frosting.
Margarine
Hydrogenated vegetable shortenings (margarine) have become a popular ingredient in commercial icings during the 20th century because they are cheaper and more stable at room temperature, and therefore easier to work with than butter. The whiter color is also favored, especially for wedding cakes. However, shortening does not dissolve in the mouth like butter, leading to a heavy, greasy feel inside of the mouth. The flavor of the buttercream is also not as intense, and the resulting product raises health concerns due to the presence of polyunsaturated and trans fats.
Additions
Flavorings are commonly present in a buttercream frosting. Vanilla and chocolate are the most common additions, with coffee also a popular flavoring. Clear vanilla extract can be used to create a lighter-colored frosting. For chocolate buttercreams, cocoa powder or melted chocolate is added during the creaming stage or towards the end. Liqueurs or extracts, such as almond or peppermint, can also be added. For meringue-type and French buttercreams, the sugar syrup can be prepared with finely grated citrus zest or liquids such as juice for increased flavor. Food coloring can be added easily to any buttercream.
Handling
Most buttercreams can be left at room temperature without melting. Buttercreams made with shortening and a higher sugar content withstand warmer temperatures better than those made solely with butter. Cooling buttercream will cause it to harden. If a frosted cake is cooled, the buttercream may crack.
For French buttercream, it is better to leave the cakes with butter cream covered in plastic wrap in the refrigerator. Remove them 10 or 15 minutes before serving or longer to mitigate the chill.
When using buttercream to frost a cake, it is best to work with it when it is soft and spreadable. Icings may be stored, covered, in therefrigerator for several days. Before use, the icing needs to sit outside the fridge so it can come up to room temperature. If it must be warmed quickly or if it curdles, it can be heated over warm water (such as a bain marie or double boiler) and beaten until it becomes smooth again. Avoid directly heating the buttercream.
