Brown ground beef in a skillet and drain.I also rinse mine with warm water to remove as much fat as possible. Add chopped onions & pepper. In a casserole dish, layer ground beef and sliced potatos until dish is full.Mix soup with 1/2 can of water and whisk until well mixed. Pour soup over casserole. Bake covered at 375 for 1 hour. remove lid, sprinkle with shredded cheese and bake just long enough to melt cheese.