Stir in the milk, starting with two Tablespoons and gradually add more one teaspoon at a time until you reach your desired consistency.
For thick glaze that can be piped onto the cookies, the glaze should slowly fall from a lifted spoon.For a glaze that the cookies can be dipped into, it will fall more quickly and in thinner streams.
To color the glaze, add a drop of gel food coloring. Stir to thoroughly combine the color in the glaze.
To create a swirl pattern, drop a darker gel color into the colored glaze and lightly swirl it around.
Dip each cookie into the glaze, twisting to make sure the entire surface is covered.
Gently lift the cookie up allowing the excess glaze to drip down. At first it will seem to pour off, them it will taper off to an occasional drip.
Place the cookie on a wire rack over parchment paper or a baking sheet. Sprinkle with decorative sugar while the glaze is wet!
If not using decorations, pop any bubbles that arise with a toothpick while the glaze is still wet.
Notes
Set glazed cookies aside to harden before moving or stacking, at least 12 hours.
The more you dip the cookies into the swirl glaze, the more the color will combine.
If the glaze is too thick, add additional milk. If the glaze is too thin, add more powdered sugar.
The standard flavors for cookie glaze are vanilla and almond, but orange, mint, and lemon are delicious as well.
Use a clear extract to keep the glaze color “clean”. Pure vanilla extract will change the color of your glaze.