Preheat oven to 425°F (220°C). Remove giblets from the chicken. Pat the chicken completely dry inside and out with paper towels and place it in a roasting pan.

In a small bowl, combine the softened butter, minced garlic, chopped rosemary, chopped thyme, lemon zest, 1.5 tsp salt, and 1 tsp black pepper. Mix until well combined.

Gently loosen the skin over the breast and thighs. Rub about two-thirds of the garlic herb butter directly onto the meat under the skin. Spread the remaining butter over the outside of the skin. Season the chicken all over with additional salt and pepper. Place the halved lemon inside the chicken cavity.

Roast in the preheated oven for 70-90 minutes. The chicken is done when juices run clear and a meat thermometer inserted into the thickest part of the thigh reads 165°F (74°C).

Remove the chicken from the oven and let it rest on a cutting board for at least 15 minutes before carving. This is crucial for juicy meat. Serve warm.