Crown Roast of Pork with Chestnut Sausage Stuffing

Name: Crown Roast of Pork with Chestnut Sausage Stuffing
Ingredients: Two 8-chop racks of pork (about 5 pounds each); 3 tablespoons olive oil; 2 tablespoons chopped fresh rosemary; 1 tablespoon kosher salt; 2 teaspoons freshly ground black pepper; 3 cups Chestnut and Sausage Stuffing, recipe follows; One 1-pound loaf country white bread, cut or torn into 1-inch pieces; 1 pound bulk Italian pork sausage; 4 cloves garlic, smashed and roughly chopped; 2 stalks celery, diced; 1 medium bulb fennel, diced; 1 medium yellow onion, diced; 4 tablespoons unsalted butter, plus additional for buttering casserole dish; Kosher salt and freshly ground black pepper; 1/2 cup chopped fresh Italian parsley; 1 tablespoon chopped fresh sage; 1 tablespoon chopped fresh thyme; 2 cups jarred whole roasted and peeled chestnuts, roughly chopped; 2 1/2 cups chicken broth