Place the Oreos in a large ziplock bag, seal, and crush using a rolling pin into fine crumbs. Alternatively, place the Oreos In a food processor, and pulse until the Oreos are finely ground, about 30 to 45 seconds. Place the crushed Oreos in a medium bowl, and stir in melted butter until well combined and the mixture holds together when squeezed.

Press the Oreo mixture firmly into an even layer in the bottom of a 9x13-inch baking dish. (I like to use the bottom of a glass for this.) Freeze until firm, at least 30 minutes.

In a large mixing bowl or the bowl of a stand mixer fitter with the paddle attachment, beat together the cream cheese, sugar, and 2 tablespoons of milk on medium-high speed until smooth and fluffy, about 2 minutes. Fold in one of the containers of Cool Whip until just combined. Spread the cream cheese mixture into an even layer over the crust. Refrigerate for 10 minutes or until it feels firmer to the touch.

In a large bowl, whisk together the pudding mix and the remaining 3 cups of milk until smooth and thickened, about 2 minutes. Spread in an even layer over the cream cheese layer. Refrigerate for 10 minutes or until set.

Spread the remaining container of Cool Whip in an even layer over the chocolate pudding layer. Garnish with mini chocolate chips, loosely cover with plastic wrap, and refrigerate until set, about 4 hours or overnight.