I think this may be similar to what you are looking for.

Chilled Chocolate Pie

1 baked graham cracker pie crust

melt 30 large marshmallows in 1/2 cup milk in double boiler. Add 6 ounces chocolate chipes. Cool. Stir in a 12 ounce carton of CoolWhip. Refrigerate. May add more or less Cool Whip to increase or decrease chocolate flavor.