Chicory Leek Soup

Name: Chicory-Leek Soup
Ingredients: 6 tablespoons unsalted butter; 2 large leeks, white and tender green parts only, chopped; 1/2 teaspoon celery seeds; 1/2 teaspoon caraway seeds; 6 pounds chicory, tough outer leaves discarded, the rest chopped; 2 1/2 quarts chicken stock; 2 tablespoons apple cider vinegar; 2 tablespoons mild honey; Salt and freshly ground white pepper