Preheat the oven to 350℉/180℃ and line a muffin tin with liners and set aside. Mash the bananas and set aside.
In a bowl, add the flour, baking soda, baking powder cornstarch, cinnamon, and salt. Stir to combine and set aside.
2 cups all-purpose flour, 1 tsp baking soda, 1 1/2 tsp baking powder, 1 tsp cinnamon, 2 tsp cornstarch, 1/4 tsp salt
In another bowl, add the brown sugar, white sugar, mashed bananas, oil, eggs, vanilla, and sour cream. Whisk well to combine. The batter may be lumpy from the bananas, that is normal.
1/2 cup dark brown sugar, 1/4 cup white sugar, 2 large eggs, 1 tbsp vanilla, 1/2 cup oil, 1 cup bananas, 1/3 cup sour cream
Add the dry ingredients in and with a spatula, gently fold until a soft muffin batter forms. Do not over-mix!
Fill the liners halfway, then swirl some Biscoff in. Fill the rest of the liners to the top and swirl more Biscoff on top.
1/2 cup Biscoff
Bake for 22-28 minutes or until a toothpick inserted comes out clean. Allow to cool, and enjoy!