Preheat oven to 325F. Line your pan with parchment paper or coat with grease. Honestly, parchment is the way to go. It’s always going to keep your food from sticking. If you don’t have any just be sure to grease the pan really evenly. Heat your nut butter until easily stir-able. This can be done on the stove top or in a microwave safe bowl. If microwaving, heat in 30 second intervals and stir each time until the butter softens.
Next combine the nut butter with the sweet potato and vanilla extract in a large bowl. In a separate bowl, stir together the dry ingredients. Like really well: none of that clumpy nonsense.
Pour dry into wet (the order is important), and combine until smooth. The dough will seem quite thick for a brownie batter. Dump into the prepared pan and tap against the counter to settle it evenly into the pan and use an additional sheet of parchment paper to press against the batter and smooth it out evenly. Bake in the center of your oven for 20 minutes. They will look a bit underdone but will set once they have cooled all the way. Once the pan is cool you can transfer them to the fridge to set them faster.
Notes: Any form of nut butter works for this recipe. Different butters will yield slightly different textures and flavors. Use crunchy peanut butter to add some more texture to the brownies or canned yams for added sweetness.