In a medium bowl, add wet ingredients: grated zucchini, Greek yogurt, honey, avocado oil, eggs, and vanilla. Combine well.
In a large bowl, whisk together white whole wheat flour, cocoa powder, baking powder, baking soda, salt, and cinnamon.
Add wet ingredients to large bowl with dry ingredients and mix until just combined. Fold in chocolate chips.
Prepare a non-stick loaf pan by spraying with cooking spray or lining with parchment paper.
Pour batter into loaf pan and top with extra chocolate chips.
Bake at 350 degrees on the middle rack for 50-55 minutes. Bread is finished when a toothpick or fork comes out clean.
Notes
White whole wheat flour is sometimes also called "golden wheat". You can also use all regular whole wheat flour, all white flour, or half and half!For a lower sugar loaf, use just 1/3-1/2 cup of honey. Just keep in mind, it won't be as sweet and the zucchini flavor will come through more.