Preheat your oven to 400°F (200°C).
In a small bowl, mix the softened butter, minced garlic, chopped thyme, chopped rosemary, half of the salt, and half of the pepper until well combined.
Pat the chicken completely dry with paper towels. Season the inside of the cavity generously with salt and pepper.
Stuff the cavity with the lemon halves and the halved head of garlic.
Gently loosen the skin from the breast meat using your fingers. Rub half of the herb butter mixture underneath the skin directly onto the meat.
Rub the remaining herb butter over the outside of the chicken legs and wings. Drizzle the exterior with olive oil and season with the remaining salt and pepper.
Place the chicken breast-side up in a roasting pan. Tie the legs together with kitchen twine if desired.
Roast for approximately 1 hour and 15 minutes to 1 hour and 30 minutes. Baste the chicken with the pan drippings every 30 minutes.
The chicken is done when the skin is golden brown and an instant-read thermometer inserted into the thickest part of the thigh reads 165°F (74°C).
Remove from the oven and tent loosely with foil. Let the chicken rest for at least 15 minutes before carving to allow the juices to redistribute.