Preheat oven to 375°F.
Line a 12-cavity muffin tin with paper or parchment liners.
In a large bowl, add banana, pumpkin, and sugar. Beat together with a hand-mixer until the mixture is smooth.
Beat in the melted butter, oil, eggs, and vanilla. Mix well.
In a medium bowl combine flour, baking soda, pumpkin spice seasoning, cinnamon, and salt. Mix with fork.
Add dry ingredients to the wet ingredients and mix with a fork until just incorporated. Ingredients should be all blended together but not overmixed.
For extra rise and fluff factor, cover the bowl of muffin batter with a clean dishcloth and allow the batter to rest for 10-15 minutes.
Use a large cookie scoop or a tablespoon to scoop the batter and divide evenly between muffin cups. Aim for a little over 3 TBSP batter per muffin cup, filling them anywhere from 3/4 full to fully filled.
For an over-the-top muffin top, mix together cinnamon and sugar and sprinkle on top of the muffins before baking. The sweet topping caramelizes a bit when baking and forms a light and irresistable crust on the tops of the muffins.
Place into the 375°F oven and set timer for 5 minutes.
When the timer goes off switch the oven temp to 350°F without opening the oven. This gives the muffins a little boost to help them rise. Bake for an additional 17-18 minutes or until a toothpick comes out clean from the center of the muffins.
Allow muffins to cool in the muffin tin for 5 minutes then transfer to a wire cooling rack and allow to fully cool before diving in face-first! Hooray muffins!