Preheat oven to 400 degrees F. Grease a mini muffin pan with 24 indentations.
Mash the bananas in a large mixing bowl. Whisk in the egg, sugar, vanilla and coconut oil.
Whisk in the baking soda, baking powder, cinnamon and salt, making sure they are evenly dispersed, then add the flour and stir with a scraper until smooth.
Stir in the chocolate chips (if using).
Fill the muffin cups almost to the top. These rise high and shouldn't spread outward, but try not to overfill to be safe.
Bake at 400 F for about 12 minutes or until they appear set and nicely browned. Let cool in the pan for a few minutes, then carefully pry them out with the tip of a knife.
Grease the muffin tin again and bake any remaining batter. You should get about 36 total.