Margarine is a suitable replacement for butter in a lot of recipes and especially buttercream. Use a margarine that has a comparable amount of fat to butter. Some margarines only contain 60 percent fat, which isn’t enough to hold up in a buttercream recipe. Stick margarine works best because it reacts in a similar way to stick butter. Look for a margarine that has at least 80 percent fat. Use margarine in equal ratio to the butter in your recipe.

Vegetable shortening is common in buttercream recipes and is often used alongside butter. Whether or not your recipe calls for shortening, you can replace all of the butter for vegetable shortening. Shortening lacks the flavor and color of butter, but it yields a pure white frosting with a stiffer consistency. Use shortening in equal parts to the butter called for in your recipe. Because vegetable shortening has a higher melting point than butter, it holds up better to high temperatures.

Cream cheese can be used in place of butter because it’s soft and has the fat content to hold the sugar and keep the frosting moist. Cream cheese has a tangy, distinctive taste that will alter your final frosting's taste. Use 3 to 4 ounces of cream cheese for every 1 cup of butter required in your recipe. Stick to the stick variety of cream cheese and don’t use flavored cream cheese. If you’re making a cake that needs to sit in higher temperatures, don’t use cream cheese, because it tends to remain soft and it can cause your cake to sag.

Whipping cream creates a fluffy, light frosting that can replace butter. For every 1 cup of butter use 3 cups of heavy whipping cream. Whip the heavy cream in a chilled mixing bowl on medium to high speed until it’s thickened and slightly fluffy. Then add in the powdered sugar in small amounts until soft peaks form. Whipped cream doesn’t yield as stable of a frosting as butter or shortening and it needs to be refrigerated.

Peanut butter can be used to replace butter in buttercream, but your frosting will have that distinct peanut butter taste. You cannot use peanut butter to replace the entire amount of butter in the recipe. Instead replace one-half of the butter with peanut butter and the other one-half with shortening. The shortening helps stabilize the frosting and the peanut butter adds creaminess and flavor.