Remove whole chicken from all bags and place breast side up in a large casserole dish. Drizzle with 1 Tablespoon olive oil and place in preheated oven. Roast for 2 to 2 1/2 hours from frozen, or 1 to 1 1/2 hours thawed.
Meanwhile, combine diced tomatoes, pearl onions, garlic, potato, and olives in a large bowl. Toss with 2 Tbsp. olive oil, salt, pepper and Italian seasoning. Set aside.
With 1 hour remaining roasting time, remove chicken from oven and scatter vegetable mixture around chicken. Drizzle all over, including chicken, with remaining 1 Tbsp. olive oil and season with additional salt and pepper. Continue roasting for 1 hour, or until chicken is done.
To check chicken doneness, insert a meat thermometer into the thigh (not touching bone). Chicken is done when internal temperature reaches 180 degrees F and juices run clear.
Let chicken rest 10 minutes before carving. Serve with vegetable mixture.