Mock Orange Chiffon Pie

1 (14 ounce) can sweetened condensed milk
1 pint sour cream
1 (9 ounce) container Cool Whip
1/4 cup powdered orange breakfast drink
1 (9-inch) prepared graham cracker
    crust or baked pastry shell
1 (11 ounce) can Mandarin oranges (optional)

Mix first 4 ingredients thoroughly and pour into prepared crust or shell. Chill well before serving.

Mandarin oranges can be used for garnishing.