This recipe can be adapted to make almost any cream vegetable soup, replacing the asparagus with 1 cup of finely chopped vegetable, such as cauliflower, celery, or broccoli.
Pour the broth in a pot and add the asparagus. Lightly sauté the onion in the butter, and also add to the broth along with the parsley. Bring to a boil, cover, and simmer until the asparagus is tender.
Drain the broth into a bowl. Put the vegetables through a food mill or puree in a food processor. Combine with the broth, and return to the pot.
Stir in the cream or half-and-half over low heat. Mix the arrowroot with a little milk, and stir into the broth. Continue stirring until the soup thickens and comes to a boil.
Taste for seasoning and serve with chopped chives or chopped parsley.