1/2 c. (1 stick) butter, softened
3 c. sifted confectioners' sugar
4 tbsp. milk
1 tsp. vanilla extract

Cream softened butter in large mixing bowl. Slowly mix in 1 cup of sugar. Then add 2 tablespoons of milk. Mix in another cup of sugar and another tablespoon of milk. Then mix the rest of the sugar and the rest of the milk. The mixture should be creamy and easy to spread. Add vanilla and beat with an egg beater until light and fluffy. For a softer frosting, add another tablespoon of milk.

Beat in food coloring along with the vanilla to make a frosting that's any color of the rainbow. Add a few drops at a time until you have the color you want.