In a large mixing bowl, beat 1/2 cup softened butter until it has a creamy texture. Add 4 1/2 cups confectioners' sugar and 1 1/2 teaspoons vanilla extract. Finally, beat in 5 to 6 tablespoons milk, or enough to bring the frosting to the desired consistency.
It is possible to change the flavor of buttercream icing by using different flavoring agents. For almond buttercream frosting, use the same amounts of butter, powdered sugar and milk, but replace the vanilla extract with 1/2 to 3/4 teaspoon almond extract. Make orange buttercream frosting by replacing the milk with 5 to 6 tablespoons orange juice and adding 1 teaspoon grated orange peel.
To make chocolate buttercream frosting, beat 1/2 cup butter until it is creamy. Blend in 1/2 cup cocoa powder, 4 cups confectioners' sugar and 1 1/2 teaspoons vanilla extract. Add 6 to 7 tablespoons milk to make the frosting easy to spread.
Wilton recommends making buttercream frosting with shortening and butter. To make this frosting, beat one stick of butter and 1/2 cup vegetable shortening in a mixing bowl. Beat in 1 teaspoon clear vanilla extract, then add 4 cups sifted confectioners' sugar, 1 cup at a time, and beat the mixture on medium speed. Add 2 tablespoons milk, and beat the frosting until it is fluffy. To make the icing stiff enough to use for decorating, omit the butter from the recipe. Add 1/2 teaspoon Wilton butter flavor and an additional 1/2 cup vegetable shortening.