1 (10 3/4-ounce) can condensed cream of chicken soup
1 large (3/4 cup) onion, finely chopped
1 rib (1/2 cup) celery, finely chopped
3 tablespoons chopped fresh parsley
1/2 teaspoon salt
1/4 teaspoon pepper
3 pounds Yukon gold potatoes, peeled, thinly sliced
Spray 4- to 5-quart slow cooker with no-stick cooking spray; set aside.
Combine all ingredients in bowl except potatoes, butter and cheese slices; mix well. Stir in potatoes until well coated. Spoon potato mixture into slow cooker; drizzle with butter.
Cover; cook 6-7 hours on Low heat setting, or 3-4 hours on High heat setting.
Stir cheese into potato mixture. Cook 5-7 minutes or until cheese is melted; stir.
When cooked on High, the top of the sauce may look curdled. Stir potato mixture to remove curdled appearance.