Ingredients 1 1/4 cups white sugar 1 cup butter 3 egg yolks 1 teaspoon vanilla extract 2 1/2 cups all-purpose flour 1 teaspoon baking soda 1/2 teaspoon cream of tartar Directions Preheat oven to 350 degrees F (180 degrees C). Lightly grease 2 cookie sheets. Cream together sugar and butter. Beat in egg yolks and vanilla. Add flour, baking soda, and cream of tartar. Stir. Form dough into walnut size balls and place 2 inches apart on cookie sheet. Don\'t flatten. Bake 10 to 11 minutes, until tops are cracked and just turning color.