In a bowl, add the brownie mix along with the ingredients necessary listed on the box. Whisk together until a thick batter is formed. Set aside.
In another mixing bowl, add the melted butter and pumpkin puree. Whisk together until combined.
Then add in the brown and white sugars, with the eggs and vanilla extract. Whisk this mixture again until smooth.
Pour in the all purpose flour and pumpkin pie spice. Blend these dry ingredients into the wet, gently mixing until a thick batter is formed. Fold in the chocolate chips.
Take the cast iron skillet and place dollops of the pumpkin batter and dollops of the brownie batter into the pan. Continue this until all the batter is used, being sure to evenly distribute the two batters.
Use a butter knife and drag back and forth through the batters for a cool swirl effect when baking.
Place in the oven and bake for 35-40 minutes or until the top is shiny and the center is cooked through.
Remove from the oven and let cool for a couple minutes.
Top with ice cream and enjoy!
Notes
Tips
Grease the cast iron skillet well to keep the brownies from sticking and to get crisp, chewy edges.
Start checking for doneness a few minutes early since cast iron holds heat and can bake faster.
Let the brownies cool in the skillet for 10–15 minutes before slicing for cleaner cuts and a fudgy center.
Storage & Make Ahead
Store leftovers in an airtight container in the refrigerator for up to 4 days.
Freeze individual pieces tightly wrapped for up to 2 months.
Warm briefly in the microwave before serving to bring back that fresh-baked texture.