Preheat the oven to 350°F. Line and spray a 9x9 baking dish, set aside.
In a small saucepan, combine the chocolate chips and butter. Heat over low heat and stir occasionally until completely melted and smooth. Set aside and allow to cool slightly.
In the bowl of a stand mixer, combine the sugar and eggs and mix until combined.
Add in the flour, baking powder and salt. Stir just until combined.
Divide the batter equally between two bowls. Set aside.
In another bowl, combine the pumpkin, oil, cinnamon and pumpkin pie spice. Whisk to combine.
Add the pumpkin mixture to one bowl of batter and the cooled chocolate mixture to the other bowl of batter. Stir each very well.
Take turns adding the chocolate batter and the pumpkin batter to the prepared pan. Once all the batter has been dolloped, use a knife to swirl the mixture together for a more aesthetic look. Sprinkle with the additional chocolate chips.
Bake in the preheated oven for 40-45 minutes.
Remove from the oven and allow to cool.
Notes
Use a butter knife to swirl the pumpkin and chocolate batters together.Line the baking pan with parchment paper. This will make it easy to lift out the brownies and cut them into perfect squares.