Spray a 9x9" pan with non-stick spray. You can also line the pan with foil if you want the ability to lift out the entire cheesecake from the pan when serving. Set the prepared pan aside.

Crush the OREO cookies in a food processor. Add the melted butter, and pulse in the processor a few more times to combine. Pour the moistened crumb mixture into the pan, and press firmly to the bottom of the pan.

Warm the hot fudge topping in the microwave for about 30 seconds. Spread evenly over the top of the crust. Place the coated crust into the freezer to help harden while you make the cheesecake filling.

With a hand or stand mixer, cream together the room temperature cream cheese and powdered sugar and mix until creamy and slightly fluffy. Mix in the whipped topping a spoonful at a time with the mixer running on low.

With the mixer running on the lowest speed, gradually add the melted chocolate to the cream cheese mixture. Stop often to scrape down the sides of the bowl. Once all the chocolate has been mixed in, mixture will be rather thick.

Spread the chocolate filling evenly over the top of the chilled crust, making sure to spread firmly and evenly into corners of the pan. Top the filling with the mini chocolate chips. Refrigerate for at least 2 hours, or overnight. Refrigeration is necessary for the filling to set up and become firm and sliceable.

Slice into 16 squares. Enjoy!