Preheat the oven to 425℉. Line a 12 tin muffin liner with 12 liners or 2 liners with 6 muffin tins in each (Your preference) and set aside.
In a medium-sized bowl, add the flour, baking powder, cornstarch, baking soda, and cinnamon. Mix together and set aside.
2 1/2 cups all-purpose flour, 1 tsp baking soda, 2 tsp baking powder, 1 1/2 tsp cinnamon, 1 tbsp cornstarch
In a large bowl, add oil, yogurt, mashed bananas, vanilla, eggs, and brown sugar. Whisk together until combined and smooth.
1 1/4 cups bananas, 1 cup dark brown sugar, 1/2 cup oil, 3 eggs, 1 tbsp vanilla, 3/4 cups Greek yogurt or kefir
Add in the dry ingredients and using a spatula, slowly fold until a soft muffin batter forms. Mix until JUST combined.
Evenly divide the batter between 16 muffin liners. Gently sprinkle some white sugar on top of each one.
2 tbsp white sugar
Bake the muffins at 425℉ for 5 minutes. Then turn the oven down to 375°F for another 12-15 minutes. The muffins are ready when they bounce back at touch or a toothpick inserted comes out clean.
Enjoy! These muffins are best served fresh or within 3 days of baking. Store the muffins in an airtight container or ziplock bag.