Preheat the oven to 425°F (220°C). Lightly grease a roasting pan with olive oil.
Clean the chicken by rinsing under cold water, then pat completely dry with paper towels and trim excess fat.
In a small bowl, whisk the melted 1/4 cup butter, 4 tablespoons olive oil, and the juice of the zested lemon.
Place the chicken in the roasting pan and pour the butter-olive oil-lemon mixture over it, working some under the skin and into the cavity with your hands.
Season the inside and outside of the chicken generously with salt and freshly ground pepper, and sprinkle chopped parsley over the outside.
In a medium bowl, combine 4 tablespoons room-temperature butter, 2 tablespoons chopped parsley, 1 tablespoon chopped rosemary, 1 teaspoon chopped thyme, the lemon zest, 6 minced garlic cloves, and paprika if using; stir until smooth.
Rub the herb butter all over the chicken, spreading it on the skin and pushing some under the skin where possible.
Stuff the chicken cavity with the halved garlic head, the tied rosemary sprigs, the thyme sprigs, and the quartered lemon. Tie the legs together with kitchen twine.
Place the chicken breast-side up in the prepared roasting pan and roast at 425°F for about 1 hour 15–25 minutes, basting once halfway through, until juices run clear when pierced or the internal temperature reaches 165°F (74°C).
When the chicken is done, baste again with pan juices, then broil for 2–3 minutes to deep‑brown the skin if desired.
Remove the chicken from the oven and let it rest 10–15 minutes before carving. Drizzle pan juices over the carved chicken and serve with lemon wedges if desired.