1. Butter bottom and sides of 9-inch pie plate.
2. Stir together graham cracker crumbs, butter and sugar until well blended. Press crumb mixture evenly on bottom and up sides of prepared pie plate. Freeze 5 minutes before filling.
3. Stir together ice cream, marshmallows and chocolate bar pieces; spoon into crust. Cover; freeze until firm.
4. Soften slightly to serve. Garnish with whipped topping, graham cracker pieces, marshmallows and chocolate bar pieces, if desired.