In a medium bowl, combine crushed chocolate sandwich cookies and melted butter, mixing until well combined.

Press the cookie mixture firmly into the bottom of a 9x13 inch baking dish to form the crust.

In another bowl, beat the softened cream cheese, powdered sugar, and vanilla extract together until smooth and creamy.

Fold in half of the whipped topping into the cream cheese mixture until well combined.

Spread the cream cheese mixture evenly over the cookie crust in the baking dish.

In a separate bowl, whisk together the chocolate pudding mix and milk until it thickens, about 2 minutes.

Spread the chocolate pudding evenly over the cream cheese layer.

Top with the remaining whipped topping, spreading it evenly over the pudding layer.

If desired, sprinkle chocolate chips on top for added decoration.

Cover and refrigerate for at least 4 hours or overnight before serving.