Spray inside of crockpot with olive oil. Chop apple into small bite size pieces. Spread dry old fashioned oats into crockpot. Pour water over oatmeal.
Pour milk over oatmeal. Stir everything together. Add maple syrup (or brown sugar), cinnamon and chopped apples. Stir everything together.
Cover and cook overnight for 8 hours on low. Scoop cooked oatmeal into bowls. Can loosen with a bit of fresh milk on top and top with your favorite fresh fruit, seeds, and nut combinations.