Mash: in a medium bowl, mash the banana until very smooth with only a few lumps.
Add: add in the flour, egg and cinnamon (if using).
Mix: with a fork or whisk, mix until everything is combined.
Cook: heat a medium skillet over medium heat, spray with cooking spray or add a little butter if needed. Drop one tablespoon of batter on the skillet and let cook for 3-4 minutes or until the sides are starting to become firm and the bottoms are golden brown. You will not see any bubbles like traditional pancakes. Flip and cook for another 2-3 minutes or until golden brown.
Serve: let cool slightly and serve.