Spray a 6 qt or larger slow cooker with cooking spray. Add ⅓ of the potatoes to the crock, covering the entire bottom. Spread them out evenly, overlapping.
Sprinkle on ⅓ each of the pepper, garlic powder, onion, bacon, and cheese, in that order.
Make 2 more layers.
Mix the cream of chicken soup and the milk together and pour over the top of the potatoes.
Put the lid on and cook on Low for 8 hours, or until potatoes are fork tender.
Serve hot.
