Preheat oven to 350°F. Line a standard loaf pan with parchment paper or grease with oil.
Grate zucchini, wrap in paper towels or a dish towel and squeeze hard to release as much liquid as possible. Set aside.
Whisk together ground flaxseed and water in a small bowl to make the flax egg. Set aside.
In a large bowl add dry ingredients (almond flour, oat flour, baking soda, baking powder, cinnamon and sea salt) and stir to combine.
In another bowl, combine wet ingredients (zucchini, flax egg, avocado, banana, maple syrup and vanilla).
Add wet ingredients into the bowl with the dry ingredients and stir until everything is combined.
Gently stir in chocolate chips. Pour batter into prepared loaf pan and top with additional chocolate chips for decoration (this step is optional, but I like to make it look pretty.)
Bake for 45-50 minutes, or until a toothpick inserted in the middle of the loaf comes out clean. Edges and top of the loaf will be a dark, golden brown color. Let cool, slice and enjoy.
Store any leftovers covered in the fridge for up to one week.