Preheat oven to 350 degrees. Line 2 muffin tins with cupcake liners.
In a large bowl, whisk together flour, baking powder, baking soda, cinnamon, and salt; set aside.
In the bowl of your mixer fitted with the paddle attachment, cream together butter, oil, and sugar until light and fluffy.
Add mashed bananas, eggs, and vanilla extract, and whip for an additional 3-4 minutes.
Gradually alternate adding the flour mixture and the buttermilk to the banana mixture in 3 additions. Begin and end with the flour mixture. Mix only until just combined.
Scoop batter into the cupcake liners 2/3 of the way full.
Bake cupcakes for 15-17 minutes or until a toothpick is inserted into the center of a cupcake and comes out clean. Remove from oven and cool completely.