Preheat the oven to 350ºF and spray a 9x5” loaf pan with cooking spray.
Cut the zucchini in half lengthwise and scoop out any large seeds with a spoon. Next, shred the zucchini using a box grater and place the shreds in a colander set over a bowl. Sprinkle with a 1/4 teaspoon salt and stir to coat the zucchini. Let the zucchini drain for 15 minutes.
While the zucchini drains, prep the ingredients. In a large bowl, whisk together the flour, oats, baking powder, baking soda, cinnamon, nutmeg and remaining ¼ teaspoon of Kosher salt. Set aside.
In a medium bowl, whisk together the sugar, oil, eggs, and vanilla until combined. Add the mashed banana and finish mixing.
Pour the wet ingredients into the dry, and mix about halfway through. There should be visible streaks of flour still.
Return your attention to the zucchini. Using a paper towel, press out any remaining liquid from zucchini. Discard the zucchini water, and add the drained, shredded, zucchini to the banana bread batter.
Fold the batter until the zucchini is just incorporated, and pour into the prepared 9x5”loaf pan.
Bake the zucchini bread at 350ºF for 50-60 minutes until risen in the center and a toothpick inserted comes out clean.
Remove the bread from the oven, let it sit in the pan for 15 minutes before turning out onto a cooling rack. Allow the bread to fully cool before slicing, and enjoy!