Preheat your oven to 350 degrees F. Coat the inside of a loaf pan with non-stick cooking spray and set it aside. (I highly recommend lining the loaf pan with parchment paper after spraying and then spraying the paper too. It makes it REALLY easy to get the loaf out of the pan.)
Beat the oil and sugar together in a large mixing bowl with a hand mixer. (Or you can use your stand mixer.) Add in the mashed banana, egg, and vanilla. Mix to combine.
In a medium mixing bowl, whisk together the flour, cinnamon, baking powder, baking soda, and salt. Add the dry ingredients to the wet and mix on low speed until just combined.
Fold the zucchini and walnuts into the batter using a rubber spatula or large spoon. Pour the batter into the prepared loaf pan.
Bake for 40-50 minutes or until a toothpick inserted into the center comes out clean.
Remove from the oven and let cool before removing from the pan and slicing.
Notes
Nutritional information is based on one loaf cut into 8 slices.