Turnip and Turnip Greens Soup

Recipe from "The Art of Simple Food" by Alice Waters
Remove the greens from:
1-2 bunches of young turnips with greens
     Trim and discard the stems from the greens. Wash and drain the greens and cut them into 1/2-inch strips. Trim the roots from the turnips. If needed peel the turnips (taste one to judge if the skins are tough), and slice thin. Warm 3 tablespoons butter or olive oilin a heavy pot over medium heat. Add 1 onion, sliced thin and cook until soft, about 12 minutes. Add the sliced turnips with 1 bay leaf, 2 thyme sprigs, and Salt.
     Cook for 5 minutes or so, stirring occasionally. Cover with 6 cups chicken broth.
Bring to a boil, then turn the soup down to a simmer and cook for 10 minutes. Add the turnip greens and cook for another 10 minutes or until the greens are tender. Taste for salt and add more as needed.
• Add a small piece of prosciutto or smoked bacon with the sliced turnips and herbs.
• Garnish the soup with grated Parmesan.
• Cook the soup in water instead of broth and stir in a couple tablespoons of butter or olive oil at the end for richness.