To your slow cooker, add all ingredients (except for those listed under "toppings") to a lined or greased slow cooker. Stir to combine.
Cover and cook on low for 6 to 8 hours. The actual cooking time will vary depending on the slow cooker you use, so it's preferable that you check for doneness after 5 hours and adjust accordingly.
After cooking is complete, allow oatmeal to cool slightly.
Serve oatmeal topped with fresh, chopped apples, pecans, and maple syrup (if desired).
The cooking time is based on the usage of steel cut oats. Do not substitute steel cut oats with any other type of oat.It's critical to grease or line the inside of your slow cooker crock before you place ingredients in the slow cooker. If you don't, the steel cut oats will stick to the side of the slow cooker crock.