In a food processor or blender, blend 36 Oreos (whole cookies) into fine crumbs. Reserve ½ cup for topping and then mix in 3 Tablespoons melted butter until combined. Press the mixture into the bottom of a 9x13-inch baking dish and place in the freezer or the refrigerator for 5 minutes.
In a medium-sized bowl, whip 8 ounces cream cheese and 5 Tablespoons butter until fluffy with an electric mixer. Mix in ⅔ cup powdered sugar and 1 teaspoon vanilla until smooth. Fold in 8 ounces Cool Whip.
In a separate bowl, whisk 2 boxes instant pudding and 2 ½ cups milk together until thick. Let sit a few minutes to thicken. Then fold the pudding into the cream cheese mixture.
Spread the filling evenly over the Oreo crust until smooth.
Sprinkle the reserved ½ cup Oreo crumbs over the top. Cover loosely with plastic wrap and chill 4 hours before cutting and serving.
