Adapted from kitchensimplicity.com
Place water, milk, banana, vanilla, cinnamon, nutmeg, salt and brown sugar (or maple syrup) in a medium-sized saucepan. Bring to a boil over medium-high heat, stirring frequently. Stir in oats. Simmer over medium heat for 8 minutes or until desired thickness. Stir in walnuts just before serving.