Preheat oven to 375 degrees. Grease a 9 x 5 baking dish and set aside.
In a large mixing bowl mash the pureed sweet potato with the nut butter, coconut flour, cacao powder, maple syrup and vanilla extract. Stir well until a thick dough forms (thin with a little water if needed), and add to the baking dish. Top brownies with extra walnuts.
Bake for 30 minutes, allow to cool, slice, and enjoy!
Reheat Frozen Brownies for a Quick Snack Anytime!
I froze these leftover brownies in an airtight bag, then heated them in the oven when I was ready to eat. They turned out PERFECTLY! The texture was still rich and fugdy even after being frozen for a few months.To reheat from frozen, place brownies on a baking sheet, and cook at 350 degreen Fahrenheit for 30 minutes until they are warm in the center and slightly crisp on the outside.