• Make-Ahead

Ingredients

1. 2 tablespoons unsalted butter
2. 2 tablespoons extra-virgin olive oil
3. 1 large onion, coarsely chopped
4. 1 quart low-sodium vegetable broth
5. 4 cups water
6. 2 1/2 pounds parsnips, peeled and cut into 2-inch chunks
7. 2 ounces thinly sliced prosciutto, cut into 1/4-inch-wide strips
8. 1/2 cup heavy cream
9. 1/2 cup milk
10. 1 tablespoon thyme leaves
11. Salt and freshly ground pepper

Directions

1. In a large pot, melt the butter in 1 tablespoon of the olive oil. Add the onion, cover and cook over low heat, stirring occasionally, until softened, about 5 minutes. Add the broth and water along with the parsnips and bring to a boil over high heat. Cover and simmer over low heat until the parsnips are tender, about 30 minutes.
2. Meanwhile, in a small skillet, heat the remaining 1 tablespoon of olive oil. Add the prosciutto and cook over moderately high heat, tossing, until crisp, about 30 seconds. Using a slotted spoon, transfer the prosciutto to a paper towel–lined plate to drain.
3. Working in batches, puree the soup in a blender until very smooth. Transfer the soup to a clean saucepan. Stir in the cream and milk and bring to a simmer over moderate heat, stirring a few times. Season the soup with salt and pepper and ladle into bowls. Garnish with the prosciutto and thyme leaves and serve.

Make Ahead

The soup can be refrigerated overnight. Reheat gently.