Preheat the oven to 350°F (175°C). Grease and line a 9x9 inch baking pan with parchment paper.

In a mixing bowl, whisk together the granulated sugar and melted butter until combined.

Add the eggs and vanilla extract, whisking until smooth.

Sift in the cocoa powder, flour, salt, and baking powder. Stir until just combined.

In another bowl, mix together the pumpkin puree, brown sugar, pumpkin pie spice, egg, and vanilla extract until smooth.

Pour half of the brownie batter into the prepared pan and spread evenly.

Spoon the pumpkin mixture over the brownie batter, then dollop the remaining brownie batter on top.

Use a spatula or knife to gently swirl the mixtures together.

Bake in the preheated oven for 25-30 minutes or until a toothpick inserted comes out with a few moist crumbs.

Allow to cool in the pan before slicing into squares.