01 - Set oven temperature to 400°F.
02 - Pat chicken dry with paper towels and place breast side up in a roasting pan or ovenproof skillet.
03 - In a small bowl, mix lemon zest, minced garlic, olive oil, rosemary, thyme, kosher salt, and black pepper.
04 - Rub marinade all over the chicken, including under the skin of breast and thighs to maximize flavor penetration.
05 - Place quartered lemon, optional garlic cloves, and half of the onion inside the chicken cavity.
06 - Scatter remaining onion, carrots, and celery around the chicken in the pan if using.
07 - Tie chicken legs together with kitchen twine and tuck wings underneath for even cooking.
08 - Cook chicken in preheated oven for 1 hour 15 minutes or until an internal thermometer reads 165°F in the thickest thigh area.
09 - Halfway through roasting, baste chicken with pan juices to maintain moisture and enhance flavor.
10 - Allow chicken to rest 10 to 15 minutes before carving. Serve with roasted vegetables and pan juices.