Preheat your oven to 375℉/190℃, and line a large baking sheet with parchment paper.
Peel and cube your sweet potatoes, place them in a pan or pot, and cover with water. Bring to a boil and cook until soft, approx 8-10 minutes. Drain and return to the pan. Then mash well using a potato masher.
Add all the remaining ingredients to the pan with your mashed sweet potato and mix well. The batter will be thick.
Use a cookie scoop to make your cookie balls and place them on your baking tray. Then, gently press each one down with a fork to flatten and shape them. Bake the sweet potato cookies for 15-18 minutes, until golden.
Remove from the oven, allow to cool for 5 minutes and enjoy.
Notes
Use very ripe bananas with brown spotted skins. Since these cookies are naturally sweetened, you want to use very ripe and sweet bananas.
If possible, use a scale to weigh your ingredients for the best results. If you do not have a kitchen scale, spoon and level your flour into your measuring cup. Don't scoop from the bag, or you may end up with too much.
If you don't have oat or brown rice flour, you may use all-purpose whole wheat flour with similar results. Use 110g (approx ¾ cup) only if you're not avoiding gluten.
You can make brown rice flour and oat flour if you don't have any on hand. I grind the ingredients in my Vitamix.
Leftovers will keep in a sealed container at room temperature for 1-2 days, refrigerated for 3-4 days, or freeze them airtight for up to 3 months.