Grease the bottom of a slow cooker with cooking spray.
Put all ingredients (frozen diced potatoes, cream of chicken soup, sour cream garlic salt, and onion) in EXCEPT 1 cup of cheese.
Cover and cook on HIGH for 3-4 hours or LOW for 5-6 (mix halfway) until potatoes are tender.
Turn off and remove the lid.
Sprinkle on the remaining cheese and cover for 10 minutes until the cheese is melted. ENJOY