Preheat the oven to 350 degrees F.
In a large mixing bowl, combine pumpkin with brownie mix and stir until smooth. Add chocolate syrup and stir until blended. The batter will be very thick, but don't add anything else!
Spray a square baking pan (9-inch by 9-inch works best) with nonstick spray. Spread the batter into the pan.
Then spoon peanut butter on top and use a knife to swirl it around.
Bake in the oven for 35 minutes. The batter will remain very thick and fudgy and it should look undercooked.
Allow the fudge to cool, then cover the pan with foil and refrigerate for at least 2 hours. Cut into 36 squares. Then get ready for a fudge frenzy!