This recipe is from Wilton’s Basic Cake Decorating
1/2 cup unsalted butter (see note)
1/2 cup solid vegetable shortening (Crisco is best)
1 teaspoon vanilla extract
1/8 teaspoon salt
1 pound (about 4 cups) confectioners sugar
3 tablespoon cool milk or cream
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 of bowl often with a spatula. Add milk and beat at high speed until light and fluffy. Keep icing covered and store in refrigerator until ready to use.
Yield: 3 cups
To use as a frosting, thin with additional 2 tablespoon milk or cream.
NOTE:
It is a good idea to chill the icing for a half hour before decorating, especially when making flowers. If you find the icing too thick, you can thin with a little water, just a few drops at a time.
If you want a whiter icing, use all Crisco ( 1 cup) instead of the 1/2 cup of butter.