Preheat your oven to 350°F (175°C) to ensure even baking.
Grease your loaf pan lightly with oil or line it with parchment paper for easy removal later.
In a large mixing bowl, whisk together the white whole wheat flour, baking powder, baking soda, salt, and ground cinnamon until well combined.
In another bowl, mash the ripe bananas until smooth. Add in the granulated sugar, brown sugar, egg, melted coconut oil, and vanilla extract. Mix until everything is well incorporated.
Pour the wet mixture into the bowl with the dry ingredients. Using a rubber spatula, gently fold the mixtures together until just combined. Be careful not to overmix!
Fold in the shredded zucchini until evenly distributed throughout the batter.
Transfer the batter into the prepared loaf pan, smoothing the top with the spatula. If desired, sprinkle the turbinado sugar on top for a sweet, crunchy finish.
Place the loaf pan in the preheated oven and bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the Zucchini Banana Bread from the oven and let it cool in the pan for about 10 minutes. Then transfer it to a wire rack to cool completely before slicing.