Preheat the oven to 350°F (180°C) and line an 8"x 8" pan with parchment paper.
Take a medium-sized bowl or a blender bowl. Add melted coconut oil and combine it with pumpkin puree, peanut butter, and vanilla extract. Mix or blend them well to get a smooth, creamy mixture.
In a separate medium-sized bowl, combine all the dry ingredients: almond flour, pumpkin spice, brown sweetener, baking soda, baking powder, and salt. Don't add the chocolate chips just yet!
Add the coconut oil and pumpkin mixture and mix for 2 minutes until completely incorporated.
Add in chocolate chips and fold using a rubber spatula until well incorporated.
Pour the batter evenly in the pre-prepared pan and bake for between 35-40 minutes. Make sure the brownies are cooked through by inserting a toothpick — it should come out still moist but kind of clean.
Remove the brownies from the oven and let them cool completely. Don't cut them until they're at room temperature.
For the optional topping, melt some chocolate chips in the microwave in 10-second intervals until smooth, and immediately drizzle over your brownies. Top with walnuts (optionally) and enjoy!