For visual instructions watch the video (link in recipe description).
Lay chicken breast side down. Using kitchen scissors cut along the backbone, staying close to the bone, right through to the butt of the chicken.
Cut along the other side of the backbone, staying close to the bone, cutting right to the end and remove the backbone.
With a sharp knife cut through the cartilage, about ¼ inch, to expose the sternum. Using your fingers bend the chicken until the sternum pops out. Now the chicken will lay flat.
Flip the chicken over and tuck the wings under.