01 - Set the oven to 300°F.
02 - Combine olive oil or melted butter, minced garlic, thyme, rosemary if using, salt, pepper, and lemon zest in a small bowl.
03 - Pat turkey breast dry. Loosen skin carefully and spread half of the herb mixture beneath it. Rub remaining mixture evenly over the skin.
04 - Place onion, carrots, and celery in a roasting pan to form a bed and pour in chicken broth.
05 - Place turkey breast skin-side up on top of the vegetable bed.
06 - Cook uncovered for 1 hour 45 minutes to 2 hours, until internal temperature reaches 165°F at the thickest part.
07 - If desired, increase oven temperature to 425°F during the last 10 minutes to crisp the skin.
08 - Remove from oven, tent loosely with foil, and let rest for 20 minutes before carving.
09 - Strain pan juices and serve alongside the sliced turkey.