Creamy Celery Root Soup With Ham

2 tablespoons unsalted butter or extra virgin olive oil
2 leeks, white and light green parts only, halved lengthwise and thinly sliced crosswise
1 large celery stalk, finely chopped
Salt to taste
1 1 1/2-pound celery root
1 large waxy potato, peeled, quartered lengthwise and thinly sliced crosswise
1 meaty ham bone
1 sprig thyme, 6 parsley stems and 1 bay leaf, tied in a bundle
½ cup heavy cream (optional)
Freshly ground white pepper to taste
1 tablespoon chervil leaves or snipped chives

Nutritional Information
- Nutritional analysis per serving (6 servings)
  286 calories; 11 grams fat; 4 grams saturated fat; 0 grams trans fat; 4 grams monounsaturated fat; 1 gram polyunsaturated fat; 26 grams carbohydrates; 4 grams dietary fiber; 3 grams sugars; 19 grams protein; 56 milligrams cholesterol; 744 milligrams sodium

6 servings

In a 4-quart saucepan, melt butter. Add leeks, celery and salt. Cover and cook over low heat, stirring occasionally, until soft, about 10 minutes. Meanwhile, quarter celery root and thickly peel, using a knife. Cut into 1-inch dice. Add celery root, potato, 6 cups water, ham bone and herb bundle to pot, and bring to a boil. Reduce heat to medium-low and simmer, uncovered, until potato is tender, about 30 minutes.
Discard herb bundle. Remove ham bone, remove meat from bone, chop meat and return meat to soup. Using an immersion blender, purée soup. Add cream, if desired, and heat. Taste and add salt if needed. Ladle soup into bowls and season with white pepper. Garnish with herbs, and serve.

1 hour