Each portion makes enough icing to decorate a single two-layer cake.
Combine butter and ½ cup water in a mixing bowl, mix at low speed.
Add vanilla and salt to bowl and mix in.
Add 4 cups of powdered sugar to bowl and mix in.
Add 8 additional cups of powdered sugar to bowl and mix in.
Add 1 tablespoon of water and blend in.
Add up to an additional 5 tablespoons of water to achieve the desired consistency.
