Preheat your oven to 350 degrees F. Line a 12-cup muffin tin with paper liners or grease each cup well with coconut oil or nonstick spray.

Peel the bananas and place them in a large mixing bowl. Mash thoroughly with a fork until almost no lumps remain. The more ripe they are, the easier this goes and the sweeter your muffins will be.

Add the eggs, maple syrup, and vanilla to the mashed banana. Whisk everything together until well combined, about 30 seconds.

Add the almond flour, baking soda, salt, and cinnamon if using. Stir with a spatula until a smooth batter forms. It will look thinner and looser than regular muffin batter. That is completely normal with almond flour, so do not add more flour.

Divide the batter evenly among the 12 muffin cups, filling each about two-thirds full. Tap the tin gently on the counter once to settle the batter.

Bake for 20 to 22 minutes. Start checking at 20 minutes by inserting a toothpick into the center of a muffin. It should come out clean or with just a few moist crumbs. Almond flour muffins can dry out quickly past this point so do not wait too long.

Remove the tin from the oven and let the muffins cool in the tin for 10 minutes before transferring to a wire rack. They firm up as they cool and are much easier to handle once fully cooled.