Preheat oven to 200°C / 400°F
Pat the chicken completely dry
Mix butter with minced garlic, herbs, salt, and pepper
Gently loosen skin and rub herb butter underneath
Season the cavity generously
Stuff cavity with lemon halves, garlic bulb, and herb sprigs
Tie legs together with kitchen twine
Place onion (if using) in the roasting pan
Set chicken on top and drizzle with olive oil or butter
Pour wine or broth into the pan
Roast until skin is golden and juices run clear
Rest the chicken before carving