1 cup butter, softened
1 tsp. vanilla
4 to 4 1/2 cups powdered sugar
1 Tbsp. milk
Cream butter and vanilla in a mixing bowl. Gradually add powdered sugar until frosting is spreadable. If frosting gets too stiff, add milk, one teaspoon at a time until frosting is the desired consistency. Frosting can be spread on cookies or cakes or piped with a decorating bag and tips.
To color frosting, I recommend using paste dyes instead of liquid dyes. They are more concentrated and will not alter the consistency of your frosting. You can purchase these at most large craft stores.