1/4 cup butter
1 large onion, chopped
1 cup chopped celery and leaves
4 cups 1/2-inch cubed potatoes
1/4 cup finely chopped parsley
1/2 teaspoon salt
1/4 teaspoon pepper
1 quart regular strength chicken broth or 4 bouillon cubes plus 1 quart water
1 quart milk
3 tablespoons cornstarch
1/4 cup water
In an 8- to 10-quart kettle, melt butter over medium heat. Add onion and celery and sauté. Add potatoes, parsley, salt, pepper and broth. Cover and cook until potatoes are tender.
Stir in the milk and cook until soup is thoroughly hot (but not boiling).
Blend the cornstarch and water until smooth. Add to soup and continue cooking until soup boils and thickens - about 5 minutes.
To serve, float a generous pat of butter on top of soup and sprinkle with chopped parsley.
Serves 6 to 8.