Preheat oven to 350°F (180°C). Line a 12-hole muffins tray with a paper liner. Slightly oil the paper with cooking spray to prevent the muffins from sticking to the paper. Set aside.
Peel the bananas, mash with a fork or potato mashed, and measure the amount called by the recipe.
In a large mixing bowl, stir the mashed banana, pumpkin puree, vanilla extract, oil, and sugar. Stir well to combine evenly.
In another bowl, whisk flour, salt, baking soda, baking powder, and pumpkin spices.
Stir the dry ingredients into the wet ingredients until just combined - don't over mix, or the muffins could come out gummy.
Transfer the batter evenly into the 12 muffin cases and bake at 180°C (350°F) for 25-35 minutes on the center rack of your oven until a toothpick inserted in the center of the muffin comes out clean
Storage
Cool on a wire rack, then store in an airtight box for up to 4 days in the fridge, or freeze for later and thaw at room temperature.