Take the tube of cookie dough and press into the bottom of a 12 inch pre-seasoned cast iron skillet. .
Prepare the brownie mix according to the package directions.
Once the brownie mix is combined, add in the mini Reese's peanut butter cups.
Pour the brownie mixture onto the cookie dough and spread out evenly.
Sprinkle Reese's Pieces on top of the brownie.
Bake in a 350 degree trailer oven, house oven or BBQ until the brownie is cooked, making sure to watch to keep the cookie bottom away from direct flames underneath it. In the BBQ, cook it on one side and have the flames on the other so the bottom of the cookie doesn't get too dark.
Let it cool so the brownie can set, about 25 minutes. Slice and serve.