01 - Set oven temperature to 425°F.
02 - Pat the chicken dry with paper towels. Rub the skin and cavity evenly with olive oil or melted butter, salt, and pepper.
03 - Place lemon halves, smashed garlic cloves, 2 thyme sprigs, and 1 rosemary sprig inside the chicken cavity.
04 - Secure legs together with kitchen twine and tuck wings beneath the body.
05 - Spread carrots, onions, and celery evenly in a large roasting pan. Layer remaining thyme and rosemary sprigs over vegetables. Position chicken breast-side up on top.
06 - Cook in the preheated oven for 1 hour and 20 minutes, or until the juices run clear and an internal thermometer inserted into the thickest thigh reads 165°F.
07 - Allow the chicken to rest for 10 to 15 minutes before carving. Garnish with chopped parsley if desired and serve alongside the roasted vegetables.