Add oats and almond milk to large bowl and let sit overnight or for at least 5 to six hours.
Pre-heat oven to 425°F and grease 12-cup muffin pan.
Add mashed bananas, egg, vanilla, oil, and maple syrup to the bowl of soaked oats and milk. Whisk until combined.
In separate bowl whisk together dry ingredients, flour, monk fruit, baking soda, cinnamon, and salt. Add dry ingredients to oat and banana mixture. Stir until well combined. Fold in nuts.
Pour batter evenly into 12-cup muffin pan. Bake 18-20 minutes or until toothpick inserted into muffin comes out clean.
Let cool for 5 minutes in pan, then transfer to wire rack to cool completely.