Preheat your oven to 400°F (200°C). Rinse the chicken inside and out, then pat it dry with paper towels.
In a small bowl, combine the softened butter, minced garlic, lemon zest, chopped rosemary, thyme, salt, and pepper. Mix well to create a flavorful paste.
Carefully loosen the skin of the chicken breast and thighs with your fingers. Rub the herb butter mixture under the skin, ensuring even distribution. Spread any remaining butter mixture over the outside of the chicken.
Place the lemon halves and onion quarters inside the chicken cavity. This will add moisture and aroma during roasting.
Place the chicken in a roasting pan fitted with a rack. This allows for even cooking and crispy skin.
Roast the chicken for 45-55 minutes, or until a meat thermometer inserted into the thickest part of the thigh registers 165°F (74°C). Baste the chicken with pan juices every 15 minutes to keep it moist.
Remove the chicken from the oven and let it rest for 10 minutes before carving. This allows the juices to redistribute, resulting in a more tender and flavorful bird. Carve and serve hot.
