1/2 c. butter
1/2 c. solid vegetable shortening
1 tsp. vanilla
1/8 tsp. salt
1 lb. box confectioners' sugar (about 4 c.)
3 tbsp. cool milk (or water)

Cream butter and shortening together with an electric mixer. Add vanilla and salt. Beat in sugar, 1 cup at a time, blending well after each addition. Scrape sides and bottom of bowl often with a spatula. Add milk and beat at high speed until light and fluffy. Keep icing covered with lid or damp cloth and store in refrigerator when not in use. Yield 3 cups.