1 lb. butter
1 c. light brown sugar
1/4 c. granulated sugar
2 egg yolks or 1 whole egg
1 tsp. vanilla
4 c. flour

Cream butter and sugar. Add egg and vanilla and mix well. Blend in flour. Chill in refrigerator for 2-3 hours. Roll into small balls. Place on cookie sheet and press flat with fork. Bake at 400 degrees for about 15 minutes.