Melt the butter in a large saucepan. Sautee onions, potatoes and leeks for approx. 2 min. Pour broth into the pan and allow to boil for approx. 25 min. Cook till vegetables are tender. Add creme fraiche and boil the soup. Add the parsley and blend the soup till completely smooth in a blender. Add salt and pepper to taste. Serve the soup in 4 deep plates. Sprinkle with crunchy Castello Tickler Extra Mature Cheddar cheeseas well as fresh apple, parsley and a dash of olive oil. Serve with coarse bread.