Combine soup, sour cream, onion, 1/4 cup butter and salt in a small bowl. Combine potatoes and cheese in the crockpot. Pour soup mixture over potato mixture; mix well. Sprinkle stuffing mix over potato mixture; drizzle with remaining 3 tablespoons butter. Cover; cook on LOW 8-10 hours or on HIGH 5-6 hours or until potatoes are tender. You could cook this in a conventional oven at 375 for about 45-50 minutes or until potatoes are tender.