Preheat oven to 300˚F. Lightly spray a 9x5-inch loaf pan with cooking spray. Line the bottom of the pan with parchment paper so the ends hang over the pan edges. Spray again with a light coat of nonstick spray. Set aside.

Add sugar and oil to a large bowl. Stir to combine. Add eggs and vanilla, stirring until smooth.

Add banana, pumpkin puree, baking soda, salt, and pumpkin pie spice. Stir until combined. Fold in flour, stirring until just combined.

Add 1/4 of the batter to the bottom of the prepared pan. Dollop 1/3 cup of Nutella over the batter and use a table knife to swirl the Nutella throughout the batter.

Top with 1/3 of the remaining batter in an even layer, then swirl with another 1/3 cup of the remaining Nutella.

Add the remaining batter on top in an even layer. Finish with the remaining Nutella dolloped on top, and give it a final swirl as well.

Bake for 65 to 85 minutes, until a toothpick inserted in the center of the bread comes out clean.

Cool for 20 minutes in the pan before removing the bread, using the parchment paper as a sling. Place on wire rack to cool completely.

Slice and serve.