Reserve 1/2 cup snack mix from bag. Lightly spray bottom of 9-inch springform pan with cooking spray. In resealable food-storage plastic bag, place remaining snack mix; seal bag, and crush mix. Place in medium bowl. Stir in melted butter, and press in bottom of pan. Refrigerate 10 minutes.
Gently spread ice cream over crust in pan. Cover with whipped topping. Sprinkle with reserved snack mix. Cover loosely with foil. Freeze 2 to 4 hours or until firm.
To serve, remove side of pan. Let stand 5 minutes. Cut with hot wet knife. Store leftovers loosely cover in freezer.