Optional: If you want to make the homemade chocolate sweet potato frosting, see the directions below Make it either the night before or a few hours in advance and chill in the refrigerator.
Cook sweet potatoes until soft and tender. (Roast in oven, steam or microwave) Allow to cool. Peel and Mash.
Preheat oven to 350°F (177°C). Grease 9 x 9 round springform pan or line a 9 x 9 cake pan with parchment paper. (see notes below for details)
Microwave the peanut butter if not liquid.
Mash the sweet potato in a large bowl. Add the pourable peanut butter and mix well. Then add 2 eggs, vanilla extract, and maple syrup. Stir well.
Add the dry ingredients, cocoa powder, baking soda, salt and protein powder and mix well to combine.
Pour the sweet potato brownie batter into the prepared 9 x 9 round baking pan. Spread the batter to the edges of the pan and smooth over the top so it bakes evenly.
Place brownies in the center rack in the oven uncovered. Bake for 23-29 minutes. As these brownies are fudgy, a toothpick will not come clean even when they are cooked. Instead use a meat thermometer and when it reads 180 degrees F it is done. (Every oven is different so check your brownies at the 20-minute mark and if they wiggle in the center when you touch them, they will need longer. If they no wiggle in the center, check temperature with a thermometer and go from there.)
Remove from the oven and allow the brownies to cool for 5 minutes in the pan. Then, carefully lift the brownies out of the pan using the ends of the parchment paper and lift and cool on a wire rack. You can even place the brownies in the refrigerator overnight covered or for a few hours and decorate later.
Once the brownies are completely cooled, use a knife to cut the circle in half. Turn the brownie and cut the circle in half the other way. Then slice into a total of 8 brownies. Keep the knife clean by dipping it in water and wiping with a towel between each slice.
Pipe on the delicious chocolate sweet potato frosting (recipe below) or your favorite frosting and decorate with a holiday sprinkles as desired. Break the gluten free pretzel rods in half. Insert the broken end of pretzel into the rounded end of the brownie tree for the base of the Christmas tree.