Preheat your oven to 350°F. Line a 4x8" baking pan with parchment paper. Then spray lightly with non-stick cooking spray.
If grinding your own oat flour, measure about 2-1/4 cups of oats and grind them in your blender. I love using my Nutribullet because it only takes about six seconds. Shred two medium zucchinis. Then place them in a mesh strainer bag, cheesecloth, or towel. Twist and squeeze all the excess liquid from the zucchini. Then discard the liquid. Combine the egg, honey, applesauce, almond milk, oil, apple cider vinegar, and vanilla in a medium-sized mixing bowl. Whisk until the eggs are well-blended. Add the oat flour, baking powder, baking soda, cinnamon, and salt to the mixing bowl. Gently whisk just until the ingredients are blended. You do not want to overmix.
Add the shredded zucchini and almost all of the chocolate chips. Gently mix with a spatula until all the ingredients are evenly distributed.
Pour the batter into your prepared pan. Sprinkle remaining chocolate chips on top. Bake for 40-45 minutes or until a toothpick comes out clean.