1In large bowl, mix powdered sugar, butter, vanilla, almond extract and egg. Stir in flour, baking soda and cream of tartar. Cover and refrigerate 2 to 3 hours.
2Heat oven to 375°F. Lightly grease cookie sheet with shortening or spray with cooking spray. Divide dough in half. On lightly floured surface, roll each half 3/16 inch thick. Cut into desired shapes with cookie cutters. On cookie sheet, place cookies about 2 inches apart.
3In small bowl, mix egg yolk and water. Divide mixture among several small custard cups. Tint each with a different food color to make bright colors. (If paint thickens while standing, stir in a few drops of water.) Paint designs on cookies with small paintbrushes. Bake 7 to 8 minutes or until edges are light brown. Remove from cookie sheet to wire rack; cool.