Wilton Buttercream Icing

This is the buttercream I use for my cakes, it's the Wilton recipe

1/2 cup solid vegetable shortening
1/2 cup (1 stick) butter or margarine softened
1 teaspoon clear vanilla extract
4 cups sifted confectioners' sugar (approximately 1 lb.)
2 tablespoons milk

Makes: About 3 cups of icing.