Chocolate Pie - cooking recipe

Ingredients

1 1/2 c. sugar
3 eggs
3 c. milk
1/2 c. cocoa
1/2 c. flour
1/2 stick butter
1 Tbsp. vanilla
2 cooked pie shells (I like graham cracker crusts)
Cool Whip

Preparation

Mix well all ingredients, except butter and pie shells and Cool Whip, in a saucepan.
Add the butter last and cook over medium heat until thick, stirring constantly.