Preheat the oven to 350 degree F. Line a loaf pan with parchment paper or lightly spray with cooking spray.
In a large bowl mash the bananas. Add eggs, brown sugar, melted coconut oil, and vanilla extract.
In a separate medium bowl, whisk oat flour, almond flour, cinnamon, nutmeg, baking powder, baking soda and salt.
Add dry ingredients to the wet and gently stir together with a wooden spoon until partially mixed together.
In a small bowl, toss blueberries with 1 tbsp. oat flour to coat.
Fold the blueberries into the batter and gently stir. It's ok if a couple streaks of flour remain.
Pour the batter into the prepared pan so that's in smooth and relatively even.
Stir together the ingredients for the crumb topping and sprinkle it over the loaf before putting it into the oven.
Bake for 45-50 minutes until a toothpick comes out with just a few crumbs. Let cool, slice and enjoy!