Place the bird breast side down on a cutting board. Using poultry shears or a large, sharp knife, cut along one side of the backbone.
Pull the bird open slightly and cur down the other side of the backbone to free it. Reserve for making stock or discard.
Turn the bird breast side up and open it as flat as possible. Press firmly to break the breastbone and flatten the bird.
Add the shallots, garlic and herbs to the butter and mix well.
Dot the butter onto the spatchcock chicken.
Roast the chicken for about 45 minutes, turning them over half way through. Turn again and baste with the cooking juices.
Roast until the internal temperature reaches 165ºF. The total cooking time will depend on a variety of factors, including the weight of your chicken and how heat circulates within your specific oven.
Remove the chicken from the oven and transfer it to a cutting board. Allow the chicken to rest for 10 minutes before slicing and serving.
