A whole chicken, especially the larger birds, can take longer to get all of the meat to a safe temperature.
So, a great way to have a roast chicken on the bone, in less time, is to butterfly or split the whole bird. This is also called spatchcocking. It is almost as simple as cutting the chicken in half but the result is a flat profile that cooks evenly.
Halving a chicken is still a good skill to learn. Simply place the whole bird length ways in front of you, breast side up. Using a long sharp knife or cleaver simply cut straight down through the middle. The breast bone will guide you.
You could even flatten each half out a bit with the heel of your hand.
Place the whole bird length ways, breast down. Using kitchen shears, cut along each side of the backbone, removing it entirely.
Then slice in into the cartilage at the top of the breastbone (see the next photo) and pop the breastbone out. Run your finger along the soft part of the breastbone and it should come out in one piece. I have embedded the excellent YouTube video that taught me how to do this at the bottom of the post.
Tidy the fat and skin up. Flip the chicken over and flatten it slightly with your hands.
How to remove the breastbone easily:
Here are more chicken primal cuts and uses of butterflied chicken: