Preheat oven to 350 degrees (F). Spray a 9x13 inch pan with cooking spray.
In a medium bowl, combine brownie mix, eggs, oil, and water. Stir and set aside.
Press the cookie dough into an even layer on the bottom of the baking dish.
Add Oreo cookies in a layer to cover the cookie dough.
Pour the brownie mix evenly over the Oreos.
Bake for 35-45 minutes or until a toothpick inserted into brownies comes out clean. Remove from oven and let set for 10-15 mins.
Slice and enjoy!