Preheat oven to 350 degrees. Grease a loaf pan with cooking spray. Set aside. In a medium mixing bowl, whisk together oat flour, almond flour, flax seed, cinnamon, baking powder, baking soda and salt. In another medium bowl, use a hand mixer to whisk together bananas, brown sugar and oil until fluffy. Whisk in egg, then vanilla extract until thoroughly combined. Slowly add dry ingredients to the banana mixture while whisking on medium speed, just until combined. Fold in shredded zucchini. Pour mixture into the loaf pan. In a small bowl, whisk together cinnamon and sugar. Evenly coat top of bread batter with the cinnamon sugar mixture. Bake for 50-55 minutes, until toothpick inserted in the center comes out clean. Allow to cool, then slice and serve.