Place the chicken breast side down on a cutting board. Using a chef’s knife or poultry shears, cut along each side of the backbone, separating the backbone from the chicken. Remove the backbone and save it for stock or discard it.
Turn the chicken, breast side up facing you, on a cutting board. With the heel of your hands, press firmly against the breastbone until it cracks and it lays flat.
Start at the neck and loosen and lift the skin around the breasts and around the thighs part of the chicken. Gently push between skin and meat (be careful not to detach skin completely) and rub salt under the skin. Place the cut butter under the skin. Sprinkle generously salt and pepper all over the cavity and the all over skin.
On a large cookie sheet, spread the lemon, thyme, sliced onion, garlic, and ginger to cover the bottom. Sprinkle with salt. Place the wire rack over the lemon onion mixture and place the flattened chicken breast side up, in the middle of the rack. Add the wine and 1 ½ cups of chicken stock.
Roast the chicken in the preheated oven. Add more chicken stock to the cookie sheet if it starts to dry out. Rotate the chicken halfway through roasting time. Poke gently with a fork the breast at the tight junction to let out any juices.
Bake for 1 to 1 ½ hours. Remove from oven and let rest for 10 minutes before carving.