Preheat your oven to 425°F (218°C). Remove the chicken from the refrigerator about 30 minutes before cooking to bring it closer to room temperature. Pat the chicken completely dry inside and out with paper towels. This is the most important step for achieving crispy skin.
Generously season the inside of the chicken cavity with salt and pepper. Stuff the cavity with the halved lemon, the halved head of garlic, and the bunch of fresh parsley. This infuses the meat with moisture and aroma from the inside out.
In a small bowl, mix together the softened butter, olive oil, chopped rosemary, and chopped thyme. Rub this mixture all over the outside of the chicken, making sure to get under the skin of the breast meat as well. Season the exterior generously with the remaining salt and pepper.
Place the chicken breast-side up in a roasting pan or a large oven-safe skillet. Arrange the remaining lemon slices around the chicken. Place in the preheated oven and roast for about 1 hour and 15 minutes, or until a meat thermometer inserted into the thickest part of the thigh reads 165°F (74°C).
Once cooked, remove the chicken from the oven and transfer it to a cutting board. Tent loosely with aluminum foil and let it rest for at least 15 minutes. Resting allows the juices to redistribute, ensuring the meat stays moist when you carve it.