Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking dish.
In a large bowl, mix together pumpkin puree, granulated sugar, brown sugar, and melted butter until well combined.
Add the eggs and vanilla extract, mixing until smooth.
In a separate bowl, whisk together flour, cocoa powder, baking powder, salt, cinnamon, and nutmeg.
Gradually add the dry ingredients to the wet ingredients, stirring until just combined.
Fold in chocolate chips if desired.
Pour the batter into the prepared baking dish, spreading it evenly.
Bake in the preheated oven for 25-30 minutes or until a toothpick inserted comes out clean.
Allow the brownies to cool in the pan before cutting them into squares.
Serve and enjoy your delicious pumpkin brownies!