This is a fun way to decorate cookies yourself, and kids love to do it. My kids did when they were young. It's a great family activity.

Egg Yolk Paint for Cookies

1 egg yolk
1/2 tsp water

food coloring

1. Beat the water into the egg yolk.
2. Divide the yolk mixture into small bowls or dishes, and color with the food coloring.

3. Paint on the cookies (before baking) with a small paint brush, one brush for each color.