1/2 c. solid vegetable shortening
1/2 c. butter
1 lb. (about 4 c.) sifted confectioners' sugar
2 tbsp. milk or water
1 tsp. vanilla extract

Cream shortening and butter; add sugar, water and vanilla. Blend on medium speed until all ingredients are well mixed. Blend an additional minute or so until creamy. Yields: 3 cups of stiff buttercream frosting.