Preheat the oven to 425° F and position a rack in the lower third of the oven.

Remove the giblets and the neck and pat the chicken dry inside and out. Generously season the inside of the cavity with salt and pepper. Gently work your fingers under the skin and rub half of the butter on the chicken breasts and the rest over the outside of the chicken. Season with more salt and pepper.

Stuff the chicken with ½ head of garlic, ½ of the onion, a few carrots, ½ lemon and thyme sprigs. Truss the legs with cooking twine and tuck the wings under the bird.

Arrange the remaining vegetables on the bottom of the roasting pan with some under the chicken to act as a rack. Set the chicken breast side up on top of the vegetables. Add a little bit of water, wine, or chicken broth if you like.

Roast the chicken for 45 minutes. Baste with the pan juices and rotate the chicken in the oven. Cook for another 30-45 minutes, or when an instant-read thermometer inserted into the inner thigh registers 155° to 160° F and the juices of the chicken run clear when tested.

Transfer the bird to a cutting board and tent with foil. Plan on adding an additional 10 minutes of time for the chicken to rest after it's been cooked. This helps seal in the juices for a tender bite every time. Remove the vegetables from the roasting pan and serve or discard. Serve the chicken hot, or refrigerate for up to 3 days.