Cream of Artichoke Soup

1/4 cup butter
1/4 cup flour
8 cups well-seasoned chicken broth
1 cup evaporated milk or heavy cream
Salt and white pepper
1 package frozen artichoke hearts
1/2 teaspoon nutmeg
Dry sherry
Garlic croutons

Cook frozen artichoke hearts in salted water according to package instructions. Allow to cool in their cooking liquid and pur