Chestnut Soup

¼ cup extra-virgin olive oil
1 cup diced yellow onions (about 1 onion)
½ cup diced leek, white and light green parts only (about 1 leek)
½ cup diced celery (about 1 celery stalk)
½ cup diced carrot (about 1 carrot)
1 clove garlic, peeled and smashed
2 teaspoons and 2 pinches kosher salt, plus more to taste
12 prunes
1½ pounds peeled and roasted chestnuts, roughly chopped
2 cups low-sodium chicken broth
1 bay leaf
4 whole cloves
1 tablespoon heavy cream
3 tablespoons Madeira
¼ teaspoon ground nutmeg
½ teaspoon fresh lemon juice
¼ teaspoon ground black pepper, plus more to taste
3 tablespoons crème fraiche or sour cream
1 tablespoon finely chopped chives.

1. In a heavy pot, heat the oil over high. When the oil is hot, add the onions, leeks, celery, carrots, garlic and two pinches of salt and stir. Cover and cook on medium-low heat for 10 minutes, stirring from time to time. Uncover, add the prunes and all but 1/2 cup of the chestnuts. Cook for 3 more minutes, stirring often.
2. Add the chicken stock, 5 cups of cold water, the bay leaf and cloves. Bring to a boil, then reduce to a simmer and cook for 20 minutes.
3. Using a slotted spoon, remove the bay leaf, cloves, and prunes from the soup. Discard the bay and cloves. Roughly chop the prunes and set aside. Transfer the soup to a blender, let cool slightly and blend in batches, being careful not to let the steam of the heat explode; or use an immersion blender and blend directly in the pot. Return the soup to the stove, add the cream, Madeira, nutmeg, lemon juice, 2 teaspoons of kosher salt, and the black pepper. Stir in the prunes and remaining chestnuts. Season with more salt and pepper, to taste. Serve with a dollop of crème fraiche and a sprinkle of chives. Serves 8. –Jill Santopietro for The Boston Globe.