This is the recipe I use. It crusts really well, tastes great and doesn't need to be refrigerated.
1 stick butter, at room temperature
3 cups powdered sugar, sifted
3 to 5 tablespoons milk
1 teaspoon pure vanilla extract
1/8 teaspoon salt (optional)*
1. Cream butter in large mixing bowl on low speed until fluffy, about 30 seconds. Add powdered sugar, 3 tablespoons of milk, vanilla and salt.
2. Blend with the mixer on low speed until the sugar is incorporated, 1 minute. Increase the speed to medium and beat until light and fluffy, 1 minute more. Add more milk if the frosting seems too stiff.
The addition of salt helps to cut the sweetness. You can add more or less for desired taste.