Add 25 Oreo cookies to a food processor or blender and pulse until you get fine crumbs. (You may need to work in batches, try to avoid overcrowding the food processor so the cookies crush evenly.)
14.3 oz pack regular Oreo cookies, divided
In a bowl, mix the crushed Oreo cookies with melted butter until well combined. Reserve 1 ½ cups of the crumbs for the pudding layer and for topping.
6 Tbsp unsalted butter, melted
Transfer the mixture to a casserole dish (I used a 10.5x7.5-inch dish) and press it evenly into the bottom to form a firm crust.
Place the dish in the refrigerator to chill while you prepare the next layer.
In a bowl, beat softened cream cheese, vanilla and sugar until creamy and smooth. Add 4 oz (half the tub) of cool whip and mix until fully combined.
8 oz cream cheese, softened, 1 tsp vanilla extract, 1/4 cup granulated sugar, 8 oz cool whip, divided
Remove the dish from the fridge and spread the cream cheese mixture evenly over the crust. Return to the fridge while you prepare the pudding layer.
In a large bowl, whisk together cold milk and chocolate pudding mix until it begins to thicken.
2 1/2 cups whole milk, 3.9 oz Instant chocolate pudding mix, 1pack
Once thickened, gently fold in 1 cup of the reserved Oreo crumbs.
Spread the pudding evenly over the cream cheese layer.
Add dollops of the remaining 4 oz of Cool Whip on top, then spread into an even layer.
8 oz cool whip, divided
Sprinkle the top with the remaining ½ cup of crushed Oreos. Cover and chill in the fridge for 4–6 hours or overnight. Slice, serve, and enjoy!
Chocolate bar shavings, optional