How to Make It
Adjust oven rack to lowest position. Heat oven to 450° F. Combine 1 tablespoon of the oil, chopped rosemary, garlic, lemon zest, ½ teaspoon salt, and 1/4 teaspoon pepper in a small bowl.
Use your fingers to carefully loosen the skin from the breasts, thighs, and drumsticks. Spread the mixture evenly under the skin. Rub the remaining tablespoon of oil over the skin. Sprinkle with ½ teaspoon of the remaining salt and ½ teaspoon pepper. Place the lemon halves, rosemary sprig, and remaining ½ teaspoon salt inside the cavity.
Place a rack in a large ovenproof skillet or small roasting pan. Place the chicken in the pan. Tuck the wings beneath the chicken, as if it were placing its arms behind its head. Roast for 20 minutes. Add 1 cup water and roast until the chicken is cooked through and the thigh meat registers 180° F on a meat thermometer, about 40 minutes more.
Use a spatula to loosen the chicken. With a wad of paper towels in each hand, transfer the bird to a cutting board. Let it rest for at least 15 minutes before carving.