Preheat the oven to 350°F (180°C). Line a loaf pan with parchment paper.
In a medium mixing bowl, combine the oat flour, almond flour, flaxseed meal, baking powder, baking soda, and salt.
In a larger mixing bowl, mash the bananas. Add in the sugar, almond butter, milk, cinnamon, and vanilla extract.
Add the dry ingredients to the wet and gently mix with a spatula (don’t overmix the batter).
In a small bowl, mix the brown sugar with cinnamon for the cinnamon swirl.
Pour half the batter into the loaf pan. Sprinkle cinnamon sugar on top. Cover with the rest of the batter. Go in with a knife and create a beautiful swirl by making up and down movements.
Bake for 45 minutes at 350°F (180°C), fan.
Let it cool down completely before slicing (this is very important as the texture improves while cooling).