2 1/2 c. sifted flour (flour must be sifted)
1 tsp. baking soda
1/2 tsp. cream of tartar
1 c. butter, softened
1 1/2 c. sugar
3 egg yolks
1 tsp. vanilla

Preheat oven to 350 degrees. (Grease cookie sheets.) Sift together flour, baking soda and cream of tartar onto waxed paper. Set aside.

Beat together butter and sugar in bowl until fluffy, about 3 minutes. Beat in egg yolks and vanilla. Gradually add flour mixture in 4 parts, beating well after each addition. Shape dough into balls, using 1 level tablespoon for each ball. Place balls 2 inches apart. Do not flatten. Bake at 350 degrees for 12 minutes or until lightly golden around edges. Remove to wire racks to cool.