Preheat your oven to 350 degrees. Line your loaf pan with parchment paper and spray with non-stick baking spray.
In a large mixing bowl, whisk together the flour, hazelnut meal, salt, baking soda and cinnamon. Set aside.
In a separate large mixing bowl, mix together the egg, coconut oil, applesauce, coconut sugar, vanilla and mashed bananas until combined. Using a rubber spatula, slowly fold in the flour mixture into the wet ingredients just until combined. Lastly, gently mix in the grated zucchini and the dark chocolate chunks if using. (Feel free to save some of the zucchini to sprinkle over the top of the bread before baking.)
Pour the bread mixture evenly into your prepared loaf pan and sprinkle some zucchini over the top of the bread. You can also add a few dark chocolate chunks on top if desired. Bake for 60 minutes, or until a toothpick inserted comes out clean. Remove from the oven and allow to cool before slicing. Enjoy!