This recipes makes 3 cups of each flavor of frosting, if that ends up being more than you to Neapolitan a few boxes of crispy marshmallow squares, you can save the leftover icings for dipping other store-bought baked goods like brownies or doughnuts. The idea is to make the Neapolitan Icing flavors, then dip to your heart's content.These icings will start to stiffen as they sit. They will be good for 1/2 hour after you mix them up. If you want to make them in advance and use them later, place them in a bowl and lay a damp paper towel directly on the surface. And then cover the bowl with plastic wrap and leave at room temperature. If necessary, whisk in an additional 1-2 Tbsp. hot water to recapture proper consistency.