Bring water to a boil over medium high heat. Add milk. When milk comes to a simmer, add oats and salt. Cover and simmer over low heat, stirring occasionally. If you like your oatmeal with a little texture, simmer for 10 minutes. If you like it creamier, simmer for 20 minutes. Let stand covered, for 5 minutes. Stir in maple syrup, vanilla, freshly grated nutmeg and mashed banana. Transfer oatmeal to 4 serving dishes. Top with yogurt, Banana-Nut Topping and freshly grated nutmeg.
Combine slivered almonds, crushed banana chips, brown sugar and melted butter.