Preheat the oven to 350℉.
In a bowl, mix together the sugar and the melted butter. Then, mix in the eggs and the vanilla. In another bowl, add in the flour, baking powder and the salt. Now, combine the dry and wet ingredients. At this point, split the batter into two portions.
For one portion, fold in cocoa powder, pecans and chocolate chips. For the second portion, fold in the canned pumpkin and pumpkin spice.
In a lined baking pan, add in half chocolate portion first. Then, pour in all of the pumpkin part. Lastly, drop dollops of the chocolate across the pumpkin batter. Then, take a knife and swirl it through the batter.
Place in the oven and bake for 45 minutes. Adjust the time if you like brownies slightly undercooked.
Allow them to cool, then serve them warm or store for later.