Potato Leek Soup

6 leeks, white part only, cut into thin rounds and cleaned well
1 white onion
1/4 cup butter
6 potatoes, peeled and sliced
6 cups chicken stock (I use vegetable bouillon)
1/2 cup chopped fresh parsley
1 egg yolk, beaten
salt and pepper
2 cups light cream
crisp bacon, crumbled

Saute leeks and onions in butter until soft but not brown. Add potatoes, bouillon, and parsley, simmer until vegetables are soft. Strain and sieve vegetables and return puree to broth. Add some broth to egg, stirring. Then add egg to broth with seasonings. Add cream and reheat but do not boil. Garnish with bacon. Serves 8. Instead of sieving, I use a stick blender to puree. A regular blender can also be used.