2 1/2 c. sifted flour
1 tsp. baking soda
1/2 tsp. cream of tartar
1 c. softened unsalted butter
1 1/4 c. sugar
3 egg yolks
1 tsp. vanilla
Food coloring, if desired

Preheat oven to 350 degrees. Grease cookie sheets. Sift together first 3 ingredients. Set aside.

Beat butter and sugar with mixer until fluffy (about 3 minutes). Beat in egg yolks and vanilla. Gradually add flour mixture in 4 parts, beating well after each addition until well blended.

Shape into 1 inch balls. Place 2 inches apart on prepared cookie sheets. Do not flatten. Bake at 350 degrees for 12 minutes or edges are lightly golden. Remove to racks to cool. Makes 3 1/2 dozen.