Chicken and Salsa Verde Panini

INGREDIENTS:

6 Chicken pieces or
1 sm Whole chicken; skin removed
3 qt ;Water
1 Onion; finely chopped
2 Garlic cloves
-- minced or pressed
2 Celery stalks; fine chopped
1 To 2 carrots; finely chopped
2 tb Cornstarch; dissolved in
1/3 c ;Cold water (opt'l.)
2 Rosemary sprigs, 3" each