Preheat the oven to 400 F (205 C) for 20 - 30 minutes. Line (1 - 2) 12 count muffin pan with 12 cupcake liners. I recommend alternating filled cups with empty cups for the best rise.
In a mixing bowl, whisk the flour, baking powder, baking soda, ground cinnamon, pumpkin pie spice and salt together until well combined.
2 cups (240 g) all purpose flour, 2 teaspoons baking powder, ½ teaspoon baking soda, 1½ teaspoons ground cinnamon , 1½ teaspoons pumpkin spice, ½ teaspoon salt
In another bowl whisk the mashed banana, pumpkin puree, oil, granulated sugar, light brown sugar and eggs together until well combined. Mix the dry ingredients into the wet until just combined.
1 cup mashed banana , 1 cup (240 g) canned pumpkin , ½ cup (118 ml) oil , ½ cup (150 g) granulated sugar, ½ cup (100 g) light brown or dark brown sugar, 2 large eggs (US), room temperature, 2 teaspoons (10 ml) vanilla extract
If you would like to top the muffins with the recommended cinnamon sugar, whisk the granulated sugar and ground cinnamon until well combined.
3 tablespoons (38 g) coarse sugar, 1 teaspoon ground cinnamon
Use a 3 tablespoon sized cookie scoop to scoop the muffin batter into each of the muffin liners, alternating every other cup. There should be enough batter to fully fill the muffin wells. If there is extra, just add another cupcake liner to make a baker's dozen (13) muffins). Top the muffins with the cinnamon sugar. Bake the muffins at 400 F (205 C) for 18 - 20 minutes. The muffins are done when a toothpick inserted into the center comes about with a few moist crumbs or when a finger pressed gently into the center of the muffins quickly bounces back. Be careful as the cinnamon sugar will be very hot.
Cool the pumpkin muffins in the muffin pan for 5 - 10 minutes. Carefully remove the muffins to cool to room temperature and enjoy.