In a large bowl, combine the cracker crumbs and butter. Pat three-fourths of the mixture into an ungreased 13-in. x 9-in. x 2-in. dish. Refrigerate.
In a bowl, whisk the milk and pudding mixes for 2 minutes. Stir in ice cream until blended. Spread over crust. Spoon whipped topping over pudding layer; spread evenly over top.
Combine the chopped candy bar and the remaining crumb mixture; sprinkle over the whipped topping. Cover and freeze for at least 2 hours. Yield: 12-15 servings.