1. In medium bowl, mix powdered sugar and butter with spoon or electric mixer on low speed. Stir in vanilla and 1 tablespoon of the milk.
2. Gradually beat in just enough remaining milk to make frosting smooth and spreadable. If frosting is too thick, beat in more milk, a few drops at a time. If frosting becomes too thin, beat in a small amount of powdered sugar.

Notes

1. Allow your butter to soften at room temperature so it easily and smoothly beats up with the powdered (also called confectioner’s) sugar.
2. If you want to color the frosting, simply add a drop or two of food coloring to a small amount of the frosting.  If the color is too dark simply stir in  a little more frosting to lighten the color.