Preheat your oven to 425F
Pat your chicken dry if it was in brine. Lay breast down with wings facing you. Cut along the right side of the spine.
Cut the left side of the spine and reserve the spine for a great chicken broth.
Cut the sternum with a knife to allow the chicken to open flat.
Open the chicken and season with 1 tablespoon of your herbed butter.
Slice your onions and place them in your pan to form a barrier between the pan and the chicken.
Add your chicken to your pan and press down on the breast to ensure it is laying flat.
Tuck your wings to prevent them from burning.
Separate the skin from the breast, thigh, and drumstick. Insert the herbed butter under the skin. Reserve ⅓ of your herbed butter to top the chicken.
Cover the chicken with the remainder of your herbed butter.
Bake at 425F for 45 minutes or until your thermometer reads 165F. Let Chicken cool uncovered for 15 minutes and then dig in!