Edible Egg-Yolk Paint for Baking
egg yolk per container
1/4 teaspoon water per container
In each container, mix one egg yolk with 1/4 teaspoon water and many drops of food coloring. Use a paintbrush to apply paint to freshly baked cookies; return cookies to oven until paint hardens.
When mixing paint, keep in mind the age of your young artist. As a general rule, younger children require thicker paint and brushes. Adjust water as necessary for your child.