Preheat oven to 350 degrees. Using a large bowl, combine the butter and both sugars.
Stir in the egg and vanilla. Add in the flour, baking soda and salt and mix together. Add in the chocolate and peanut butter chips and combine.
Transfer cookie dough to a 9 or 10 inch cast iron skillet and bake for about 25 to 30 minutes, or until golden brown and set in the center.
Wait patiently for about 5 minutes to cool, or grab some spoons and DIG IN and ENJOY!!