Now it’s time to make the icing. You’ll need 4 cups of powdered sugar, sifted if lumpy, 1 large egg white, 1 teaspoon vanilla extract, an icing applicator, candies, sprinkles, coconut, etc.
Again from Scout Regalia:
Mix all ingredients on medium speed with an electric hand mixer until icing is smooth. Icing should have the consistency of caulk or spackle, and should be thick enough to hold form but thin enough to go through a pasty bag. Add more powdered sugar or vanilla extract as needed. Place the icing in the icing applicator and in the fridge until you’re ready to use it, but be quick, because we found it hardens quite quickly.