Cream together:
1 cup butter
1 cup shortening
2 cups sugar
6 eggs

Add: 
7 cups flour
2 tsp. baking soda
4 tsp. cream of tartar
3 tsp. vanilla

Chill dough - usually for more than two hours.  
Roll out on floured surface.  
Sprinkle with flour if desired.  
Bake at 425 for 6-8 minutes. (Don’t grease the tin!)