Preheat the oven to 350F degrees and line a 9x9-inch baking pan with parchment paper and set aside.
Combine the dry brownie mix, pure pumpkin, flour, pumpkin spice, baking soda, and vanilla in a large bowl or stand mixer fitted with a paddle attachment and beat until thoroughly combined.
Transfer the batter to the prepared baking pan and spread out evenly with a rubber spatula. Top with chocolate chips and sprinkles if desired.
Bake for 40 to 45 minutes until a toothpick comes clean when inserted into the center of the cake.