Don't let the term "crusting buttercream" scare you! This frosting develops the slightest "crust". It's something that most people would not even notice when biting into a slice of cake. However, if you are cake decorator using the Viva Paper Towel method of smoothing or an impression mat (as in our quilted buttercream video), you'll need a crusting frosting. A frosted cake develops its "crust" after sitting out about ten minutes. When lightly touched, it will leave an impression without removing any frosting. You can reduce the amount of sugar used in this recipe for an even lighter crust. I often do this when making this recipe for cupcakes (use 4.5-5 cups of confectioners sugar). Another way to reduce the amount of "crust" is to use whole milk or cream. This won't prevent crusting altogether, but it will give you a softer result than if you were using skim milk or water as your liquid.