Add the pack of Oreos to a food processor, and crush into fine crumbs.
In a medium bowl, pour in the cookie crumbs and melted butter. Stir well until combined.
Pour into a 9 x 13 baking dish and use a spatula (or your hands) to evenly press the crumbs across the dish.
In the same medium bowl, add the cream cheese and beat with a hand mixer until fluffy. Add in the 2 tbsp of milk and sugar and mix well.
Add one of the 8 oz Cool Whip containers into the cream cheese mixture, and mix with a spoon or silicone spatula. Spread the cream cheese mixture over the cookie crust, and put it into the fridge to set for 10 minutes. (Waiting the full 10 minutes makes the next steps much easier, as the cream cheese will be more firm, and the chocolate pudding mixture will spread more evenly without mixing together)
While the cream cheese mixture is setting, in a large bowl, add the pudding mixes and 2 ¾ cups of milk and beat on medium speed until it starts to thicken.
Spread the pudding mixture over the cream cheese layer. Put back into the fridge to set for another 10 minutes.
Once set, gently spread the remaining 8 oz of Cool Whip over the pudding layer, being careful not to mix the two layers together.
Cover and let chill for at least 4 hours in the fridge or 1 hour in the freezer.
Once fully set, sprinkle with chocolate chips, and slice and serve.
This can be made up to 3 days in advance (keep refrigerated).