Preheat oven to 350ºF. Spray a 9x9" square dish with cooking spray and set aside.
In a mixing bowl, combine the brownie mix and pumpkin. Stir until smooth (this takes a bit of elbow grease).
Pour into prepared dish, smoothing down the top. Spoon peanut butter in globs on top of brownie mix and lightly swirl around top with a knife until marbled throughout.
Bake for 35 minutes in preheated oven. Cool. Cut into 1 1/2" squares and enjoy!
Notes
*store in an airtight container. These are best eaten within a day or two. *adapted from the Hungry Girl Cookbook