Bring milk and water to a boil in a saucepan over medium-high heat, stirring frequently.
Place hot milk mixture, apple, and next 5 ingredients in a slow cooker coated with cooking spray, stir well. Cover and cook on LOW 7 hours or until oats are tender.
Ladle oatmeal into individual bowls; top with maple syrup and hazelnuts. Yield: 4 servings (serving size: 1 1/4 cups oatmeal, 1 T. syrup, and 1 1/2 tsp. hazelnuts).
Notes
As you can see, we didn't have any nuts so I just used some blueberries. Also, I used a slow cooker liner which would REALLY help with clean up.