3/4 lb. salted butter
2/3 c. shortening
1/4 c. milk or half and half
3 tsp. vanilla extract
4 c. confectioners sugar
1/2 c. cocoa powder, optional
Blend together salted butter along with shortening. Blend well adding milk or half and half, & vanilla extract.
Slowly add confectioner's sugar, 1/2 cup at a time, until you reach desired consistency for spreading & decorating. (This consistency is a personal preference, you can always thin it out with a few drops of milk, or thicken it by adding a little more confectioner's sugar.
For chocolate buttercream, sift in 1/2 cup cocoa with confectioner's sugar, and incorporate 1/2 cup at a time until blended.
This frosting keeps well in freezer for about 3 or 4 months.
The amount of confectioner's sugar you will need is based on how fluffy you like your buttercream. A looser consistency will have a creamy texture and will be easy to frost, however, it will be more difficult to pipe designs, roses, so on.