Finishing some of Cheryl's drafts...
Keeping spatchcocking simple. Using a VERY sharp cleaver or kitchen shears -- not scissors, carefully cut down both sides of the backbone as shown. Be slow and steady and take your time. This is the MOST difficult part. Period. Once the backbone is removed I recommend that you save it for stock.
Sorry for the blurry photo but this is suppose to show scoring or cutting through of the sternum. On a chicken this may not be necessary as normally applying firm pressure on the breast is enough to get it to crack and break. When the bird is flipped over you want it to be pressed as flat as possible.
Bird is now "flattened" with the cracked, pressed sternum and is ready for seasoning
At this point you could marinate over night in your favorite or season now, liberally on both sides. Give it 20 in the fridge and then grill or smoke.
WHY bother? This method encourages faster and more even cooking. If you are smoking, this improves the distribution of the smoky flavors as well. This opens the door to many different ways to prepare your birds of all sizes and shapes. We've done this on cornish hens up to turkeys. I wouldn't recommend for a fatty bird (duck/geese).
Buen provecho and thank you for keeping Cheryl's memories alive.