Preheat oven to 375°. Pat chicken(s) dry with paper towels and put two lemon halves and 3 cloves of garlic in the cavity of each chicken.
Tie legs together with kitchen twine. Rub 1 tablespoon of olive oil then squeeze the juice of half a lemon over each chicken. Season generously with kosher salt and black pepper. Sprinkle half of the Italian parsley over the chicken.
Add 1 cup chicken broth, or water if not making pan sauce, to the bottom of the roasting pan. Roast, uncovered, in 375° oven for 40 minutes.
Rotate pan and increase oven temperature to 425°. Roast for an additional 30-40 minutes, until internal temp of the thickest part of the breast is 170°.
When chicken(s) are done, transfer to platter and tent with aluminum foil.
Place roasting pan over medium flame. Add remaining 1 cup stock and juice of one lemon, stir with rubber spatula being careful to get up all the browned bits on the pan. Allow sauce to reduce by about half. Turn off the heat and add remaining tablespoon of Italian parsley.