Preheat oven to 350 degrees
In a large bowl add brownie mix, oil, water, and eggs and mix until combined.
In a medium bowl add cookie mix, butter and egg and mix until combined.
Add brownie mix to a 12 inch cast iron skillet *see notes
Gently spread cookie mixture into the center of brownie mix. Sprinkle extra chocolate chips on top
Bake 40-45 minutes . Remove from oven and cool a bit before serving.