If you you don't want it to be too sweat, add only 2 cups of confectioners sugar.

1/2 cup shortening
1/2 cup butter, softened
1 tsp vanilla
2 (3-4) cups confectioners sugar
2 tbs milk

1/2 cup shortening 1/2 cup butter, softened 1 tsp vanilla 2 (3-4) cups confectioners sugar 2 tbs milk

Cream shortening and butter, add vanilla. Add confectioners sugar little by little, then add milk.