Preheat oven to 350F. Prepare & bake cake mix as directed on package in 2 9-inch round baking pans. Cool 5 minuntes; remove from pans. Cool completely on wire racks.
Microwave chocolate & butter in small microwaveable bowl on high 2 minutes or until butter is melted. Stir until chocolate is melted. Cool 5 minutes.
Beat cream cheese & sugar in large bowl with electric mixer on medium speed until well blended. Gently stir in whipped topping & 12 crushed cookies.
Place 1 cake layer, top side down, on serving plate. Spread top of layer with cream cheese mixture. Cover with remaining cake layer, top side up. Spoon chocolate glaze over top of cake. Top with remaining Oreos. Let stand until set. Store in refrigerator.