For crumb crust, in a bowl stir together crushed wafers, margarine, and 1 tablespoon sugar with a fork. Press mixture into the bottom and up the sides of a 9-inch pie plate. Bake in a 375 degree F oven for 5 minutes. Cool.
For filling, in medium saucepan combine marshmallows and milk. Cook and stir over medium heat until marshmallows are melted. Remove from heat. Stir in peppermint extract and red food coloring, if desired. Pour into a metal bowl. Chill until mixture begins to thicken, stirring occasionally.
Remove the peppermint mixture from the refrigerator (it will continue to set). In a medium mixing bowl immediately beat the egg whites with an electric mixer at medium speed until soft peaks form (tips curl). Gradually add the 3 tablespoons sugar, 1 tablespoon at a time, beating on high speed until stiff peaks form (tips stand straight).
When peppermint mixture is partially set (consistency of unbeaten egg whites), fold in the egg white mixture. Fold in the thawed dessert topping. If necessary, chill the filling about 30 minutes or until it mounds when spooned. Spoon the filling into the crumb crust. Cover and chill for 4 to 24 hours or until set. If desired, garnish with additional dessert topping and mint leaves. Makes 8 servings.
Spoon filling into crust. Cover and chill for 4 to 24 hours or until set. If desired, garnish with additional whipped topping and fresh mint.