In a large microwave-safe bowl, combine marshmallows and orange juice. Microwave, uncovered, for 1 1/2 minutes on high. Stir until smooth. In a mixing bowl, beat cream cheese. Add marshmallow mixture; beat just until smooth. Fold in cool whip.
Combine Nilla wafer crumbs and butter; set aside 3/4 cup for topping. Press remaining crumbs into an ungreased 13x9 inch pan. Spoon cream cheese filling over crust. Sprinkle with reserved crumbs.