1) Mix all of the ingredients together. Stir until smooth; a fork works fine.
2) The glaze should be thick, but soft enough to "settle" when you spread it. If the glaze is too thick, dribble in another teaspoon of milk, 1/2 teaspoon at a time.
3) Add food color, if you like; gel paste food colors are preferable, as they yield vibrant color, and don't alter the liquid/sugar ratio as regular food colors might.
Yield: 2/3 cup glaze.