Preheat the oven to 350ºF and line a 9-inch square pan with parchment paper. In a large bowl, combine the mashed sweet potato, almond butter, cacao powder, coconut sugar, flour, baking powder, vanilla extract, and salt. Stir well, until a relatively smooth batter is formed. (You can do this in a food processor, if you prefer.)
Fold in the chocolate chips, if using. Transfer the batter to the prepared pan and use a spatula to smooth the top. Bake at 350ºF until the edges look dry and the center of the brownies have puffed up, about 35 to 40 minutes.
Let the brownies cool completely before slicing, or they will be too soft. Cut them into 16 small squares, and store the leftovers in an airtight container in the fridge. I think they taste even better when you serve them cold from the fridge the next day! Leftovers can be stored in the fridge for up to a week, or in the freezer for up to 3 months.
Nutrition information is for 1 of 16 pieces. This information is automatically calculated, and is just an estimate, not a guarantee.*These brownies are very fudgy, so it's normal for them to stick to your knife as you cut them. If you prefer a less-fudgy brownie, I recommend adding 1/4 cup more flour to this recipe to help cut-down on the sticky factor. I prefer King Arthur's All Purpose GF flour, but when that's hard to find I'll use their cup-for-cup blend.