Put 3
tablespoons butter or margarine into a mixing bowl and
beat with a whisk or mixer at low speed until
fluffy. Add about a cup of sifted
powered sugar and
continue beating.
Add 1 tablespoon milk and 3/4
teaspoons
vanilla, an additional 1 1/3 cup (or so) of powdered sugar and continue beating. Add more milk if you need it to make the frosting
smoother.
This recipe makes enough to frost a one-layer cake. I usually add an
ounce of cocoa and make it
chocolate.