If you don't have sweet potato on hand, you'll need to prepare that first and allow time for it to cool. Either peel, cube and steam for 15 minutes before mashing and cooling or bake in the oven on a baking pan, poked with a few holes, until fork tender. Let cool then scoop flesh out of peel, mash and cool.
Preheat the oven to 350 °F (180 °C). Prepare an approximately 8-9 inch square baking pan with a light coating of non-stick spray, lightly grease with oil or line with parchment paper.
Add the mashed sweet potatoes, coconut sugar, almond butter and coconut milk to a mixing bowl and mix well until completely combined and smooth.
Add the rest of the ingredients and mix until the flour is incorporated. Fold in the chocolate chips, if using. If you're adding anything else, like chopped walnuts, add those now as well. The batter does contain gluten, so try to avoid over mixing. As soon as the flour is incorporated stop mixing and only fold a few times to mix in the chocolate chips.
Transfer the batter to the prepared baking pan. Sprinkle more chocolate chips over top, if desired. Bake for 25 minutes.
Remove from the oven and let cool in the pan for at least 15 minutes. The longer they cool, the denser, fudgier and firmer they'll be, so completely cooling in the pan is ideal.
Slice the brownies and serve as is or lightly warmed with a scoop of your favourite ice cream or whipped cream!