Buttercream frostings are light, smooth mixtures of sugar, butter, and/or shortening. They are extremely popular because of their versatility.
They are wonderful for decorating and can be flavored and colored for different purposes or situations.
Butter vs. Shortening in Buttercream Frosting
Buttercream frostings are made with either butter or shortening. Butter makes for a much better flavored frosting; shortening makes a more stable frosting. Especially in warm weather, a butter-based frosting may melt. Because shortening melts at a much higher temperature, it is more stable. Because it does not melt in the mouth as does butter, it has a “plastic” feel that you might find unpleasant.
Stabilizing Your Buttercream Frosting
A compromise of butter and shortening often works well. The butter improves the flavor and mouth feel while the shortening helps stabilize the frosting. Egg whites or meringue powder  can also be used to help stabilize the frosting.
Easy Buttercream Frosting
This is an easy, no-cook buttercream frosting that works very well for decorating. Because it has a high butter content, it has a nice flavor and mouth-feel. It is a stable frosting in all but the warmest weather.
- 1 cup butter, softened
- 2/3 cup shortening
- 1 lb. powdered sugar
- 2 tablespoons meringue powder
- 1/2 teaspoon lemon juice
- 1 teaspoon vanilla extract 
- milk as needed for consistency
- With the paddle attachment and your stand-type mixer, beat the butter, shortening, powdered sugar, and meringue powder together.
- Add the lemon juice and vanilla. Beat the frosting, adding enough milk to reach the desired consistency.
Baker’s notes: You may use one egg white in place of the meringue powder. (Meringue powder is mostly dried egg white.)
Always apply your buttercream frosting at room temperature. Your frosting may be stored in the refrigerator for up to three days.
(Updated from May 12, 2014)