Set aside 10 to 12 Oreos for topping. Crush the remaining cookies into fine crumbs.
Stir cookie crumbs with melted butter until evenly coated. Press firmly into the bottom of a 9×13-inch dish. Chill while you make the filling.
Beat softened cream cheese until smooth. Add sugar and milk and beat again until creamy.
Fold in 8 ounces whipped topping. Spread evenly over the crust.
In a separate bowl, whisk instant pudding mix with cold milk for about 2 minutes until thickened. Let stand 3 to 5 minutes, then spread over the cream cheese layer.
Spread the remaining 8 ounces whipped topping over the pudding layer.
Crush the reserved Oreos and sprinkle over the top.
Cover and refrigerate at least 4 hours (overnight is best) before slicing and serving.