Preheat oven to 350 degrees F. Line a 8x4 loaf pan with parchment paper.
In a large bowl, make the flax eggs by combing the ground flaxseed and water. Stir and set aside for 5 minutes to thicken.
In a medium bowl, add the oat flour, almond flour, baking soda, baking powder, cinnamon, and salt. Whisk until combined.
In the bowl with the flax eggs, mash the ripe bananas. Then add the vanilla, oil, maple syrup, and apple cider vinegar. Whisk until well combined.
Add the dry ingredients into the bowl with the wet. Stir with a spatula until just combined. Don’t overmix! Fold in blueberries.
Pour batter into the lined pan. Top with more blueberries and sprinkle some oats on top (optional).
Bake for 65-70 minutes, or until golden brown on top and a toothpick inserted comes out clean. Since it is a denser loaf, this needs a longer bake time. Let it cool in the pan for 15 minutes. Then transfer bread to a cooling rack to cool completely. Enjoy!