Boudin Blanc–Stuffed Turkey Breasts with Chestnuts

Name: Boudin Blanc–Stuffed Turkey Breasts with Chestnuts
Ingredients: ½ cup kosher salt; ¼ cup sugar; ¼ cup sweet white wine (optional); 2 skin-on, boneless turkey breasts (about 4 lb. total); 2 tablespoons coarse fresh breadcrumbs; ¼ cup heavy cream; 1 cup low-sodium chicken broth; ½ cup roasted chestnuts from a jar; 1 tablespoon Cognac or brandy; 2 bay leaves; 1 teaspoon kosher salt, plus more; 1 teaspoon yellow mustard seeds; ¾ teaspoon coriander seeds; 1 whole allspice; 1 whole clove; ¾ teaspoon white peppercorns; 1 pound ground pork belly or ¾ ground pork and ¼ finely chopped bacon; 1 tablespoon finely chopped fresh thyme; ⅛ teaspoon ground mace; ⅛ teaspoon ground nutmeg; ¼ cup (½ stick) unsalted butter; 2 cups roasted chestnuts from a jar; 4 sprigs thyme; Kosher salt and freshly ground black pepper