In a medium-sized mixing bowl, whisk together milk, applesauce, maple syrup, vanilla, cinnamon, ginger, nutmeg and salt until well incorporated. Stir in oats.
Cover and refrigerate for at least four hours, or overnight.
Heat oil in a small skillet over medium-low. Add walnuts and toast for 2-3 minutes, stirring often.
Add brown sugar, salt and cinnamon. Stir well and continue toasting for 2-3 more minutes, stirring and watching carefully so they don't burn.
Transfer to parchment paper to cool. Top overnight oats with walnuts, apple slices, maple syrup, etc.
