Chocolate Cream Pie

1 1/4 cups Sugar

1/4 cup Cornstarch

1 cup Evaporated Milk

1 cup Hot Water

3 eggs, Yolks only

1/2 stick Butter

2 ounces (melted) unsweetened chocolate

1 teaspoon vanilla

Mix all dry ingredients first, then add a little of the evaporated milk to wet dry ingredients. Add 3 egg yolks and beat good. Add remainder of cream and hot water. Cook over medium heat stirring constantly. When thickened, remove from heat add butter, melted chocolate and vanilla. Pour into cooked pie shell. Cool and top with cool whip.