Coat inside of slow cooker with cooking spray.
Mix together oats, brown sugar, cinnamon, ginger, nutmeg, cloves, and salt. Grate apples and carrots in a food processor or hand grater.
Place all ingredients into slow cooker (except for toppings); stir well to combine. Cover with lid and cook on low 6 to 8 hours.
If desired, serve topped with walnuts, diced apple, dates, or raisins.
Per serving: 274 calories, 4 grams fat (2 grams saturated fat), 5 milligrams cholesterol, 195 milligrams sodium, 53 grams total carbohydrates, 6 grams fiber, 8 grams protein.