Whisk together the vanilla extract, cinnamon, mashed banana, and melted butter. Add the eggs and whisk again to combine.

Add the yellow cake mix and stir with a rubber spatula until just combined. Do not over mix.

Distribute the muffin batter into 12 lined muffin cups

Bake the banana muffins at 350 degrees for 20 - 23 minutes, until a toothpick inserted comes out clean

Cool the muffins for 5 minutes in the pan, then transfer to a wire rack to cool

Store in an airtight container in the fridge once cooled