In a bowl, combine the cereal, brown sugar, peanuts and coconut. Drizzle with butter; stir until combined. Press half of the mixture into an ungreased 13-in. x 9-in. x 2-in. dish. Cut ice cream into 3/4-in.-thick slices; arrange evenly over crust. Top with remaining crumb mixture; press down lightly. Cover and freeze until serving.