• 6¼ cups water
• 1 large leek, halved lengthwise and rinsed well
• 1 medium onion, quartered
• 2 celery stalks, roughly chopped
• 1 medium carrot, roughly chopped
• 2 cups roasted, shelled and skinned chestnuts (1 pound in shell or about 1½ (7½-ounce) jars peeled whole)
• Salt
• Freshly ground black pepper
• 1 tablespoon extra-virgin olive oil
• 2 (½-inch-thick) slices rustic Italian bread, crusts discarded, cut into ¼-inch cubes

Combine water, leek, onion, celery and carrot in a large saucepan. Bring to a simmer and cook for 35 minutes. Add chestnuts and cook until chestnuts are tender, about 25 minutes more. Remove from heat.

Using tongs, remove vegetables from broth and discard. Remove 4 chestnuts and set aside.

Purée soup in 3 batches in a blender until smooth, transferring to a bowl. Transfer into cleaned pot, bring to a simmer and season to taste with salt and pepper. Remove from heat and cover to keep warm.

Heat oil in a large skillet over medium heat. Add bread cubes and cook, tossing occasionally, until lightly golden, about 4 minutes. Cut reserved chestnuts into small pieces. Ladle soup into bowls. Top with bread cubes and reserved chestnut pieces, and serve.