Preheat the oven to 350°F. Grease or line a 9x5 loaf pan.
In a large bowl, whisk together the whole wheat flour, oat flour, baking soda, baking powder, cinnamon, salt, ground flaxseed, and chia seeds.
In a separate bowl, whisk together the eggs, Greek yogurt, brown sugar, granulated sugar, melted butter, and vanilla extract. Add the wet ingredients to the dry ingredients and mix until just combined.
Fold in the shredded zucchini, chocolate chips, and any optional add-ins you are using.
Transfer the batter to the prepared loaf pan. Sprinkle a few extra chocolate chips on top if desired.
Bake for 50–60 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached. Allow the loaf to cool in the pan for 15 minutes, then transfer it to a wire rack to cool completely.