Preheat your oven to 350°F (176°C).
Blend oats in a food processor until a fine oat flour forms.
In a bowl, mash bananas until smooth with no large lumps.
Add oat flour and baking powder to the bananas.
Mix in water, vanilla extract, salt, and maple syrup if using.
Stir until just combined, then let the batter rest for 5 minutes.
Fold in your preferred add-ins like chocolate chips, blueberries, or walnuts.
Pour the batter into a greased muffin pan (3 large or 5–6 small).
Bake large muffins for 20–22 minutes or small muffins for 16–18 minutes.
Let cool slightly before removing from the pan. Enjoy your Healthy Banana Oat Muffins warm or at room temperature.