1 (9 inch) baked pastry shell or crumb crust
1/3 c. cocoa
1 1/4 c. sugar
1/3 c. plus 1 tbsp. cornstarch
1/4 tsp. salt
3 c. milk
3 tbsp. butter
1 1/2 tsp. vanilla
sweetened whipped cream or Cool Whip

Combine cocoa, sugar, cornstarch and salt in double boiler pan. Blend in milk until smooth. Cook in the double boiler over medium heat until mixture comes to a boil. Boil and stir for 3 minutes. Remove from heat; blend in butter and vanilla. Pour into pie shell. Carefully press plastic wrap directly over the pie filling. Chill 3 to 4 hours. Serve with sweetened whipped cream or Cool Whip and chocolate curls, if desired.