Preheat the oven to 170°C/340°F. Prepare a muffin tray with 12 muffin tins.
Add flour, sugar, cinnamon, baking powder and salt to a bowl and mix well. Set aside.
Add the bananas to a bowl and mash with a fork. Add the banana puree, melted butter, tahini, egg, milk and vanilla extract to a big bowl an stir well. Add the dry ingredients and mix until everything is combined.
Divide the batter to the muffin tins. Sprinkle with some oat flakes and sugar.
Bake for 20-25 minutes until slightly golden on top. Allow to cool before you enjoy them. They taste amazing with some butter and honey or maple syrup!