Place the potaoes with onion and the bacon in crock pot. In a large mixing bowl, combine cream cheese, broth, cream of chicken soup and pepper. Add to crock pot and stir together with potato soup mixture. Cook on low for 6 to 8 hours or high 3 to 4 hours. Mash potatoes slightly before serving to thicken soup. Before serving add one or two handfuls of cheddar cheese.