Preheat oven to 350 degrees Fahrenheit. Grease a 24-cup mini muffin pan and set aside.
In a large bowl, add your banana and mash with a fork or potato masher. Then, add granulated sugar, brown sugar, oil, egg, milk, and vanilla extract. Stir until well combined. Set aside.
In a separate bowl, whisk (or sift) together the dry ingredients: flour, baking soda, baking powder, cinnamon, and salt. Pour dry ingredients into the wet ingredients and stir until just combined (do not overmix, this can cause your muffins to turn out tough).
Distribute batter between 24 mini muffin cups. Optionally, sprinkle tops with turbinado sugar. Bake for 11-13 minutes, or until a toothpick inserted into the center of muffin comes out clean (or with crumbs, not batter).
Remove from oven and allow pan to cool for 2-3 minutes before removing muffins to a cooling rack to cool completely. Store cooled muffins in a sealed container.
Muffins will keep at room temperature in a sealed container for 3 days.
Baked muffins can be stored in the freezer for up to 3 months in a freezer safe container.
If using paper liners, allow your muffins to cool completely before unwrapping, or they will stick to the papers.