Preheat oven to 325 degrees. Spray a 10-inch skillet with non-stick cooking spray.
In a large bowl, combine brownie mix with water. Once combined, fold in the peanut butter, milk chocolate chips, and dark chocolate chips.
Pour the brownie mixture into the skillet.
In another small bowl, combine cookie mix and melted butter. Take the cookie mixture and sprinkle it over the top of the brownie mixture. Sprinkle more chocolate chips on top if desired.
Bake the brownie for about 35 to 40 minutes. Remove from oven and let cool slightly before serving.
Garnish with vanilla ice cream and melted nut butter.