Preheat oven to 375 ℉
Spray the mini muffin tins with non stick cooking spray, set aside
In a medium mixing bowl combine the 2 cups all-purpose flour, 1 tsp baking powder, 1 tsp baking soda, 1 tsp ground cinnamon, and ½ tsp salt. Set aside
In a medium microwave safe bowl, melt the ½ cup butter, then add the 1 cup mashed banana, ⅔ cup light brown sugar, 2 large eggs and 1 tsp vanilla extract. Whisk until smooth
Add the dry ingredients to the wet ingredients and stir to combine until an even batter forms. Do not over mix. If you are using any add-ins stir them in at this point. (A total of 1 cup maximum).
Let the batter sit for 15 minutes to activate the baking powder and baking soda for tall muffins.
Scoop the batter into the mini muffin trays about ¾ full. You should get 32-36 mini muffins. (if you want large muffins you should get 1 dozen)
Bake for 8-10 minutes (check at 8 minutes). The mini muffins do not take very long to cook. They are done when a tester is inserted in the center and comes out clean.
Let the muffins cool for 5 minutes in the trays then remove them to a cooling rack to cool completely. Enjoy.