PREPARE cake batter and bake in 2 (9-inch) round pans as directed on package. Cool cakes in pans 10 min. Invert cakes onto wire racks; gently remove pans. Cool cakes completely.
MICROWAVE chocolate and butter in small microwaveable bowl on HIGH 2 min. or until butter is melted. Stir until chocolate is completely melted. Cool 5 min.
MEANWHILE, beat cream cheese and sugar in large bowl with mixer until blended. Gently stir in COOL WHIP and crushed cookies. Stack cake layers on plate, spreading cream cheese mixture between layers. Spread top with chocolate glaze; let stand until firm. Keep refrigerated.