Preheat oven to 350 F. Peel and mash bananas in a medium bowl with a potato masher or fork. Make sure they are well-mashed, with only small chunks remaining.
Stir in rolled oats and cinnamon. Set aside for a few minutes to allow the oats to soak up the moisture. If the batter is very wet/thin still, add 1-2 tablespoons of oats.
Line a baking tray with parchment paper or a silicone baking mat. (Cookies will stick if you skip this step).
Drop spoonfuls of batter onto baking tray and then shape with your fingers. Cookies do not spread out while baking, so shape them into the width and height you want them to be. This recipe will make about eight medium, 3-inch wide cookies.
Add optional toppings, if using.
Bake cookies for 17 minutes. *See notes for adjustments for smaller or larger cookies.
Remove from oven and allow to cool slightly before enjoying.
Notes
If making small 2-in wide cookies, reduce cooking time by 3-5 minutes. If making large 4-in wide cookies, increase cooking time by 2-3 minutes.Spices & Flavoring: Instead of cinnamon, try using 1 teaspoon of vanilla extract instead. Or, ¼ teaspoon of cardamom + ¼ teaspoon of cinnamon. 1 teaspoon of pumpkin spice seasoning is another good option.Toppings: dark chocolate chips or shavings, walnut halves, chopped walnuts, pecan halves, chopped pecans, sunflower seeds, smear of fruit preserves, jam or jelly, berries, raisins, dried cranberries, flaxseed, coconut or wheat germ.