Preheat your oven to 450 degrees.
Spatchcock the Turkey as per the instructions above.
Put the butter, olive oil, minced garlic, black peppercorns and bay leaves in a small pot and place it over medium heat. Once the butter has melted reduce the heat to low and simmer for 30 minutes. After 30 minutes strain it into a new container and discard the spices. Let the mixture cool.
Using an injector inject the butter mixture into the turkey. Make sure you hit the breasts, thighs and legs well. It is ok that some will run out.
Rub the butter mixture that has seeped out all over the turkey. This will allow your spices to stick better.
Mix the garlic powder, onion powder, salt and dried basil into a spice shaker and shake all over the bird on both sides. If you do not have a spice shaker you can just sprinkle or shake out of the individual containers.
Rough chop up the onion and celery.
Line a full sheet pan with aluminum foil (for easy clean up) and spread the chopped veggies out in the center.
Place the wire cooling racks on top of the veggies. This will allow more separation and air flow and also make removing the bird easier when it is cooked.
Place the spatchcocked turkey on top of the wire racks, breast side up. Tuck the tips of the wings under the bird, or they will most likely burn.
Cook on the middle rack of the over for 60-80 minutes. Times will vary depending on the size of the bird, your oven and the celestial tides. The point is to make sure you have a reliable instant read thermometer. In about 40-50 minutes pull the turkey out and check it. It will be done when the breast is 150 and the thighs are 165.
When the correct temps are reached pull it out and let it rest tented with foil for at least 30 minutes. The resting will make sure that all the juices don't just run out when you carve it.