2 cups flour
1 teaspoon baking soda
1 teaspoon cream of tartar
1 1/2 cups sugar
1 cup butter softened
3 eggs yolk
1 teaspoon vanilla extract
Preheat oven to 350°.
In a small bowl, thoroughly stir flour, baking soda and cream of tartar; set aside.
In a large mixer bowl at medium speed, beat sugar and butter until blended. At high speed, beat until very light and fluffy.
In a small mixer bowl at medium speed, beat egg yolks until thick and pale yellow. Add to creamed mixture with vanilla; beat at low speed until blended. Stir in flour mixture until well blended. Shape into balls, using about 1 tablespoon dough at a time. Place 3 inches apart on ungreased baking sheets.
Bake for 12 to 15 minutes or until golden and center is done. Cool cookies on wire racks.