Place the chicken, butter, soup, and onion in a slow cooker, and fill with enough water to cover.
Cover, and cook for 5 to 6 hours on Low. About 60 minutes before serving turn cooker to high and make biscuit dough. Drop handfuls of torn biscuit dough in the slow cooker and push down into the mixture. Cover and cook until the dough is no longer raw in the center approx 45 min.