Preheat oven to 375 degres. Spray muffin tin with cooking spray.
Cook quinoa as directed on package.
Mix together the applesauce, 3 mashed bananas (reserve the fourth one), almond milk, honey and vanilla.
In a separate bowl, mix the quinoa, oats and cinnamon. Gradually add oat mixture to the fruit mash, mixing gently.
Peel and chop the apple; fold into the batter along with the walnuts.
Pour an even amount of batter into the muffin cups. Add a slice of banana to the tops of each and bake for 20-25 minutes.
Allow to cool for 5-10 minutes before serving.