Preheat oven to 430°F/220°C (400°F or 200°C fan forced). Line a baking tray with foil or lightly grease a roasting pan.
Discard neck from inside the cavity and remove any excess fat and leftover feathers. Pat dry with paper towels.
Pour the olive oil, melted butter, wine (if using) and the juice of half a lemon over the chicken, under the skin and inside the cavity. Season chicken liberally on the outside and inside the cavity with salt and pepper. Sprinkle over the parsley.
Rub the minced garlic over the chicken, mixing all ingredients together over the chicken and under the skin.
Stuff the garlic head into the chicken cavity along with the rosemary sprigs and the squeezed lemon halve. Tie legs together with kitchen string.
Place breast-side up into baking tray or roasting pan. Roast for one hour and 15-20 minutes, basting halfway through cooking time, until juices run clear when chicken thigh is pierced with a skewer.
Baste again, then broil for a further 2-3 minutes, until golden.
Remove from the oven, cover with foil and allow to stand for 10 minutes before serving. Serve, drizzled with pan juices and remaining lemon half cut into wedges or slices.