Preheat the oven to 350 degrees f and spray a 9x5 loaf pan well with nonstick cooking spray.
Mash up bananas in a large bowl.
Combine pumpkin puree, eggs, melted butter, sugars, and vanilla with the bananas.
In a separate bowl mix together flour, baking soda, salt cinnamon, and pumpkin pie spice.
Combine wet and dry ingredients until just mixed. You do not want to overmix or your loaf will end up tough and far too dense.
Stir in chopped walnuts.
Use a rubber spatula to scrape all of the mixture into a prepared loaf pan.
Combine additional sugar and cinnamon and sprinkle over the top.
Bake for 55-60 minutes or until the toothpick inserted in the center comes out clean.
Remove from the oven and cool in the pan for 10 minutes.
Remove and continue cooling on a wire rack.