Preheat Oven to 350 F (176 C) and prepare 9x5 inch loaf pan.
Mash bananas in a medium bowl. Grate zucchini with skin on, squeeze out excess water and stir in with mashed bananas. (*see tips in post) Set aside.
Sift flours into a medium bowl. Add baking powder, baking soda, salt, and cinnamon then hand whisk together.
In the bowl of stand mixer fitted with paddle attachment on medium speed, beat together warm coconut oil and both sugars until mixed.
Add vanilla and eggs, then mix again. Scrape bottom and sides of bowl as needed.
Spoon in flour mixture until a thick but smooth batter is formed.
Remove bowl from stand mixer, pour in bananas and zucchini. Stir with a spoon.
Transfer batter to prepared loaf pan.
Sprinkle chopped walnuts across the top of batter.
Bake for 45-50 minutes until toothpick inserted comes out with small crumbs.
Place on cooling rack for 10-15 minutes before removing.
Slice and serve warm.