This frosting is amazing, especially with chocolate cupcakes! Creamy, smooth and fluffy. I recommend you do not use margarine, as it makes it a little greasy. Make sure your butter is softened, not melted, and not just at room temp. Leave it out for an hour or so before using. Works well for piping. If you are piping, or like lots of frosting, this will frost about 18 cupcakes. If you spread it on, you might get 24. Enjoy! From Allrecipes.