Preheat the oven to 350 degrees
If you haven't already mashed the bananas then add the whole bananas into a large bowl and mash until it forms into a pudding-like consistency. Then whisk together the mashed banana, eggs, vanilla, and coconut palm sugar until blended and smooth.
Slowly stir in the melted butter.
In the same bowl, on top of the wet ingredients, add the oat flour, baking soda, salt, and cinnamon.
Slowly stir just until all of the ingredients are combined, don't over mix.
Add the walnuts and stir 2-3 times until the nuts are evenly distributed. Don't forget to save a couple of tablespoons of the walnuts to sprinkle on top.
Spray a 12-cup muffin pan with cooking spray. Then divide the batter among the 12 muffin cups. Sprinkle the saved walnuts on top of the muffins.
Bake for 17-18 minutes. The muffins are done when you can insert a toothpick and there's no batter but only crumbs that stick to it.
Let the muffins cool in the pan for about 3 minutes.
Remove the muffins from the pan and place them onto a wire rack to finish cooling. Enjoy!