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. Roughly chop the pecans and set aside.
In a medium-sized bowl, add the flour, baking powder, cornstarch, baking soda, and cinnamon. Mix together and set aside.
In a large bowl, add oil, yogurt, mashed bananas, vanilla, eggs, and brown sugar. Whisk together until combined and smooth.
Add in the dry ingredients and using a spatula, slowly fold until a soft muffin batter forms. Mix until JUST combined.
Add in the chopped pecans and mix a few times. Don't overmix!
Evenly divide the batter between 12 muffin liners.
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 a toothpick inserted comes out dry with no wet batter.
