Preheat the oven to 425℉. Line your muffin tins with 16 liners and set aside. Roughly chop the pecans and set aside.
1 cup pecans
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 1/2 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, 3/4 cups Greek yogurt, 1 tbsp vanilla
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!
1 cup pecans
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.