Cheesy Potatoes

6 medium potatoes, peeled and slice 1/4-in thick
2 c shredded cheddar cheese
1 (10 3/4 oz) can condensed cream of chicken soup
1 small onion
4 T butter, melted
1 t salt
1 t pepper
1 c sour cream

Toss the potatoes and cheese; place in slow cooker. combine soup, onion, butter, salt and pepper; pout over mixture. Cover and cook on low for 8-10 hours, or until potatoes are tender. Stir in sour cream.