Line a 12 tin muffin liner with 12 liners or 2 liners with 6 muffin tins in each (Your preference) and set aside. Preheat the oven to 400°F.
In a medium bowl, add in flour, cinnamon, nutmeg, salt, cornstarch, baking soda, and baking powder. Mix together and set aside.
2 cups all-purpose flour, 1 3/4 tsp baking powder, 1/2 tsp baking soda, 2 tsp cornstarch, 1/8 tsp ground nutmeg, 1 tsp cinnamon, 1/4 tsp salt
In a large bowl, whisk the oil, brown sugar, bananas, eggs, and vanilla. Whisk until combined. It may be lumpy because of the bananas and that is okay!
2 eggs, 1 1/3 cups mashed bananas, 1 cup light brown sugar, 1/2 cup oil, 1 tbsp vanilla
Add the dry ingredients into the wet and using a spatula, gently fold until a muffin batter forms. Do not overmix.
Place the washed blueberries in a small bowl. Add 1-2 tsps of flour and gently toss around until evenly coated. The light coating of flour will absorb any extra liquid it may have before adding it into the mixing bowl.
1 1/4 cups fresh blueberries
Add the blueberries into the mixing bowl and mix a few times to incorporate. Do not overmix.
Evenly divide the batter between 12 muffin liners. You can bake them all in 1 tin, or 6 in 2 tins for a taller rise.
Add a few extra blueberries on top and sprinkle white sugar as well (optional).
Bake the muffins at 400℉ for 5 minutes, and then turn the oven down to 350℉ and continue baking for 12-15 minutes.
Allow the muffins to cool, and enjoy! These muffins stay good on your counter for up to 5 days and in the refridgerator in an airtight container for up to 2 weeks.