Remove the chicken from the refrigerator 30 to 45 minutes before cooking and pat it dry. Preheat the oven to 375°F.
Mix the softened butter with the seasonings. Gently loosen the skin over the breasts, spread some of the butter underneath, and coat the outside of the chicken with the remaining butter.
Fill the cavity with the lemon, onion, garlic, and herbs. Place the chicken breast-side up in a roasting pan, tucking the wings underneath and tying the legs if desired.
Roast for about 1 hour and 15 minutes, or until the internal temperature reaches 165°F. Rest the chicken for 15 minutes before carving and serving.