- 1 tablespoon extra-virgin olive oil
- 1 medium onion , finely chopped
- 2 ribs celery , finely chopped
- 3 cloves garlic , minced
- 3 medium zucchini , scrubbed but unpeeled, cut into 1/2-inch cubes (1 cup)
- 1 medium Yukon Gold potato , peeled and cut into 1/2-inch cubes (1 cup)
- 3 cups chicken broth or canned low-sodium broth , as needed
- 1 sprig of fresh thyme
- 1 cup evaporated skim milk
- 3 tablespoons freshly grated Parmesan cheese , plus additional for serving
- Salt and freshly ground black pepper
- Chopped fresh thyme , for garnish
Stir in the zucchini and potato. Add enough broth to barely cover the vegetables. Add the thyme and bring to a boil over high heat. Reduce the heat to low. Simmer, partially covered, until the potato is tender, about 15 minutes.
Stir in the evaporated milk and cheese. Heat until very hot, but do not boil, or the soup will curdle. Season to taste with salt and pepper.
Ladle into soup bowls, and sprinkle each serving with thyme. Pass extra Parmesan cheese on the side. Serve hot.