Prepare cake batter and bake in 2 (9-inch) round pans as directed on the package. Cool cakes in pans for 10 min. Invert onto wire racks; gently remove pans. Cool cakes completely.
Microwave the chocolate and butter in a small microwaveable bowl on HIGH for 2 minutes or until the butter is melted. Stir until the chocolate is completely melted. Cool for 5 minutes.
Meanwhile, beat cream cheese and sugar in a large bowl with a mixer until blended. Gently stir in cool whip and crushed cookies.
Place 1 cake layer on a plate, and spread with cream cheese mixture. Top with the remaining cake layer.
Spread the top with chocolate glaze; let stand 10 min. or until firm. Keep refrigerated.