Preheat the oven to 425 degrees. Place muffin cups in a muffin tin. Set that aside.
In a small bowl, mix together the flour, baking soda, baking powder, cinnamon, and salt. Set that aside.
In a large bowl, mash the bananas until pureed.
Add the melted butter, sugar, egg, and brown sugar to the mashed bananas. Mix well.
Pour the dry ingredients into the wet ingredients and mix until just combined.
Fold in the blueberries to the batter.
With an ice cream scoop or a measuring cup, add the batter to the prepared muffin tin. Sprinkle the top of the muffins with ½ teaspoon of sugar, or more if you would like.
Bake for 10 minutes at 425 degrees and then lower the temperature to 375 degrees and bake for 10-12 more minutes. The muffins are done when a toothpick is inserted into the muffin and comes out clean.