HEAT oven to 350°F.
SPRAY 9-inch pie plate with cooking spray. Mix first 3 ingredients until blended; press onto bottom and up side of pie plate. Use back of fork to make cross-hatch design around edge. Bake 14 to 15 min. or until golden brown. Cool.
MICROWAVE 4 oz. chocolate, marshmallows and 1/4 cup milk in microwaveable bowl on HIGH 1 min. or until chocolate and marshmallows are melted and mixture is well blended when stirred. Pour into crust. Refrigerate 10 min.
BEAT pudding mix and remaining milk with whisk 2 min. Stir in 1 cup COOL WHIP; spoon into crust. Cover with remaining COOL WHIP. Refrigerate 2 hours or until firm.
MEANWHILE, grate enough of the remaining chocolate to measure 1 tsp.; reserve for garnish. Draw 8 (2-inch-wide) stars on paper; place under sheet of waxed paper on baking sheet. Melt remaining chocolate as directed on package; spoon into small resealable plastic bag. Press out excess air from bag; seal bag. Cut 1/8-inch-piece from one bottom corner of bag. Use to pipe chocolate around outlines, then onto centers of stars; sprinkle with 2 tsp. nuts. Refrigerate until ready to use.
GARNISH pie with chocolate stars, grated chocolate and remaining nuts just before serving.