Mix together:

6 c. flour
2 tsp. baking powder
1/2 tsp. baking soda
1 tsp. salt

Cream together:

1 c. shortening
1 stick butter
2 c. sugar

Combine together:

3 egg yolks
1 tbsp. lemon juice
2 tsp. vanilla
1 c. sour cream
1/4-1/2 c. milk

Mix all ingredients together - roll out 1/4 inch thick, bake at 350 degrees until done.