Coat a slow cooker with nonstick cooking spray. Combine milk, 3 cups water, the oats, 1/4 cup of the brown sugar and the salt in slow cooker. Cover and cook overnight on LOW for 9 1/2 to 10 hours.
Uncover and stir in remaining 1/4 cup brown sugar. Set aside. Topping. Coat a large nonstick skillet with nonstick cooking spray and place over medium heat. Add apples and cook 4 minutes, stirring occasionally. Add brown sugar, 1 tablespoon water and dried cranberries. Cook 1 minute. Remove from heat and stir in nuts.
Stir oatmeal in slow cooker until smooth. Spoon about a cup into a bowl and add a few tablespoons of the topping. Serve warm.
