Bud's Butterscotch Pie

This recipe is one that my dad used to serve in his restaurant. I believe the recipe originally came from his sister who baked the pies for him. I have never had butterscotch pie like this anywhere else. It's a taste of heaven...

1 cup minus 1 Tbsp. flour
3 cups brown sugar
9 Tbsp. butter
4 1/2 cups milk
6 egg yolks beaten
1 Tbsp. vanilla

Combine flour, sugar and melted butter in large saucepan.
Add milk and cook until thickened stirring constantly.
Pour a small amount of mixture over eggs stirring vigorously.
Return to pan and continue cooking ten more minutes.
Add vanilla
Cool

Divide between 3 regular or 2 deep dish pre-baked pie crusts.
Keep refrigerated and serve with whipped cream on top.