Preheat oven to 350°F. Cream the butter and sugars in a large bowl with an electric mixer on medium speed for 3-5 minutes. Add the eggs and vanilla and mix well to thoroughly combine. In a separate bowl, whisk together the flour, baking soda and salt, then slowly incorporate into the mixer bowl until flour is just combined. Stir in chocolate chips. Spread the cookie dough in the bottom of a 9"x 13" baking dish that’s been lined with wax paper and sprayed with cooking spray. Top with a layer of Oreos®. Mix together brownie mix, adding an optional 1/4 cup of hot fudge topping to the mix. Pour the brownie batter over the cookie dough and Oreos®. Bake at 350°F for 45-55 minutes.