Preheat oven to 350 degrees F. Grease an 8×8 square pan.
In a large bowl, make the flax egg by combining the ground flax with water. Stir and set aside for 5 minutes to thicken.
In a medium bowl, add the oat flour, almond flour, tapioca starch, salt, cinnamon, baking soda, and baking powder. Whisk until combined.
In the large bowl with the flax egg, add the ripe bananas and mash until smooth. Add the coconut oil, coconut sugar, maple syrup, almond milk, and vanilla. Whisk until well combined.
Add the dry to the wet ingredients. Stir with a spatula until just combined. Bake for 30-35 minutes or until a toothpick comes out clean. Let it cool completely in the pan on a wire rack. Cut into squares and enjoy! I love to top it with some vegan yogurt!