Add the Oreo cookies to a food processor and pulse into fine crumbs. If you do not have a food processor, place the cookies into a large ziplock bag and crush with a rolling pin.

Reserve about ½ cup of the cookie crumbs for the topping.

In a large bowl, combine the remaining cookie crumbs with melted butter and stir until evenly coated.

Press the Oreo mixture firmly into the bottom of a 9x13-inch baking dish. Chill for 5 minutes.

Beat the cream cheese until smooth and creamy. Add powdered sugar and mix until combined. Fold in 1 cup Cool Whip.

Spread the cream cheese mixture over the chilled Oreo crust and refrigerate for 5 to 10 minutes.

In another bowl, whisk together the instant chocolate pudding mix and cold milk until thickened.

Spread the pudding mixture over the cream cheese layer and refrigerate for another 5 to 10 minutes.

Spread the remaining Cool Whip over the top layer.

Sprinkle the reserved Oreo crumbs over the whipped topping. Add mini chocolate chips, chocolate curls, or chocolate shavings if desired.

Refrigerate for at least 2 to 3 hours before serving cold.