Cheesy Crock Pot Potato Casserole

We had these at book club the other night and they are divine!!! I made some tonight and they were a big hit, super easy and super yummy.

7 medium potatoes, peeled and quartered
1/4 cup butter or margarine, melted
1 small onion, chopped
1 tsp salt
1 cup sour cream
1 can cream of mushroom soup
2 cups grated cheddar cheese

Topping:
1 pkg (6 oz) herb-seasoned stuffing mix
1/4 cup butter or margarine, melted

Place potatoes in greased 4 1/2 to 6 quart slow cooker. Add butter, onion, salt, sour cream, soup and cheese. Mix well. Pour stuffing mix evenly over potatoes and drizzle with butter. Cover and cook on low heat 6-8 hours or on high heat 3-4 hours. Makes 8-10 servings.