Snatch up parsnips while they're in season to enjoy their marvelous, rooty flavors. A touch of crisped prosciutto offers a rich contrast to the hearty simplicity of the earthy parsnips.
2 T. extra-virgin olive oil
1 lg. onion, coarsely chopped
4 c. low-sodium vegetable broth
4 c. water
2 1/2 lbs. parsnips, peeled and cubed
2 oz. thinly sliced prosciutto, cut into 1/4-in. strips (optional)
1 c. skim milk
1 T. thyme leaves
1/8 t. salt
1/4 t. freshly ground pepper