1. Preheat the oven to 325°F Line an 8-inch square baking pan with parchment paper allowing a little overhang. Spray with cooking spray and set aside.
2. In a medium bowl, mix the Oreo crumbs and melted butter together until thoroughly combined. Press the mixture into the bottom of the prepared pan. Bake in preheated oven for 6-7 minutes. Remove pan to a cooling rack. Leave the oven on.
3. While the crust is cooling, prepare the cookie dough. In the bowl of a stand mixer, beat the butter, brown sugar, granulated sugar, salt and vanilla until smooth and combined, about 1 minute. Slowly mix in the flour and mix until just incorporated. Mix in the mini chocolate chips. Set aside.
4. In the bowl of a stand mixer, cream the cream cheese and sugar together until smooth. Mix in the egg and vanilla just until incorporated. Mix in the crushed Oreos. Pour the Oreo cheesecake batter into the prepared crust.
5. Use your hands to form clumps of cookie dough. Flatten the clumps of dough in the palm of your hands to flatten them out. Distribute the cookie dough evenly on top of the cheesecake batter. You will cover most of the cheesecake batter. It doesn't matter if it isn't perfect.
6. Bake for about 30-35 minutes, until the cookie dough top feels dry and firm and the pan is set. You can give it a little shake to see if it is set. Move bars to a cooling rack and allow to cool completely.
7. Lift the cooled bars out by the overhang; cut into squares and store in the refrigerator. Serve cold or at room temperature.