Crush the chocolate sandwich cookies into fine crumbs. Mix with melted butter and press into the bottom of a 9×13-inch dish to form the crust. Refrigerate for 10 minutes.
In a bowl, beat the cream cheese, sugar, and 2 tablespoons of milk until smooth. Fold in 1 1/4 cups of whipped topping. Spread this mixture over the crust.
In another bowl, whisk the pudding mixes with 3 1/4 cups of cold milk until thickened. Spread over the cream cheese layer.
Spread the remaining whipped topping over the pudding layer. Sprinkle with mini chocolate chips and pastel sprinkles.
Refrigerate for at least 4 hours or overnight before serving.