Try Betty Crocker's Vanilla Buttercream Frosting recipe.
Ingredients:
3 cups powdered sugar
1/3 cup butter or margarine, softened
1 1/2 teaspoons vanilla
1 to 2 tablespoons milk
Directions:
In medium bowl, mix powdered sugar and butter with spoon or electric mixer on low speed. Stir in vanilla and 1 tablespoon of the milk.
Gradually beat in just enough remaining milk to make frosting smooth and spreadable. If frosting is too thick, beat in more milk, a few drops at a time. If frosting becomes too thin, beat in a small amount of powdered sugar. Frosts 13x9-inch cake generously, or fills and frosts an 8- or 9-inch two-layer cake.
Find more frosting and icing recipes at the following sites:
AllRecipes
Cupcake Project
Tip! Learn How to Frost the Perfect Cupcake at Life As A Strawberry.