Preheat oven according to back of brownie mix box. Spray an 8×8 baking dish with cooking spray. Combine brownie mix, eggs, and oil as directed on the back of the box, but do not add the water. Add ice cream and hot fudge to the brownie batter and stir to combine. Pour half of the brownie batter into the baking dish. Cover brownie batter with a single layer of Oreos, then top with remaining batter. Bake according to back of the brownie mix box.