Preheat the oven to 350 degrees. Spray a 13 x 9 pan with baking spray and set aside. You can also line it with parchment paper so that it is easy to pull out.
In a large bowl, combine the cake mix with one egg and the melted butter. Press the mixture into the bottom of the prepared pan. It might look like there isn’t enough to cover the bottom of the pan, but there is! Be sure to press the mixture out until it reaches the ends. Use the back of a spoon or your fingers.
In another bowl, beat the cream cheese until smooth. Add in the other two eggs and beat until fully combined. Add in the powdered sugar and Oreos and beat until it’s light and fluffy.
Spread the cream cheese mixture on top of the red velvet mixture. Bake for 30 minutes or until the cake is a light brown color on top.
Let it stand for at least 30 minutes then cut into bars and serve.
Alternatively (my preference), after the bars cool, set the pan in the fridge for 1 hour or so. Cover the pan with aluminum foil. Serve them at room temperature, but this will help them have a “fudgy” texture.