Focaccia Stuffing with Sausage and Chestnuts

INGREDIENTS

• 3 Tbs. extra-virgin olive oil
• 1 yellow onion, diced
• 3 celery stalks, diced
• 1/2 tsp. kosher salt
• Freshly ground pepper, to taste
• 1 cup peeled and roasted chestnuts, halved
• 1 1/2 lb. Italian sausage, casings removed
• 1 package (1 lb.) La Brea Bakery focaccia stuffing
• 3 to 4 cups turkey or chicken stock, warmed