1/2mini Reese's cupsquartered, reserve half for topping
Preheat oven to 375 degrees F. Line a cast iron skillet with parchment paper and set aside.
In a stand mixer or large bowl, cream together the butter and peanut butter for 1 minute, or until just mixed. add the sugar, brown sugar, baking soda and baking powder and mix again until incorporated. Scrape down the sides of the bowl as needed.
Add the egg, vanilla extract and flour and mix until combined and no flour clumps remain, 1 minute.
Fold in the chocolate chips and Reese's just until mixed through.
Add dough to the prepared cast iron skillet. Sprinkle with remaining Reese's.
Place in preheated oven and bake for 25 to 30 minutes, until toothpick inserted comes out clean.