I May Have Got Grey Cup Weekend Wrong, But I am Sure about This

From Popular Science: How to Cook the Perfect Turkey

Happy cooking! The Perfect Bird
The centerpiece of the dinner has a puzzle built right in. You have a 15 or so pound object—the turkey—made of two different types of meat that must remain stuck together, at least until after a dramatic table presentation just before serving. The white meat, or breast, is delicate, low in fat, and is at its juiciest at about 155ºF. The dark meat doesn't begin to get tender until its collagen-rich connective tissue turns to gelatin. And that doesn't get going until around 165º. So how can you get both in the oven at the same time, take them out at the same time, and keep them at the correct temperatures throughout?
Food-science expert Harold McGee, author of the encyclopedic culinary reference On Food and Cooking, has come up with the answer. He builds in a temperature differential before putting the turkey in the oven, giving the leg meat a head start at heating up.
Here's how he does it: A couple hours (no more than three) before cooking, he moves the turkey from the fridge to the counter and places sealable plastic bags filled with crushed ice on the breast. As the legs warm up, the breast stays cool. When the breast meat is around 40º and the leg meat is close to 60º, he puts the bird into the oven. It's done when the breast meat reaches between 155º and 160º and the dark meat around 180º. Both meats are perfectly cooked. For perfect browning, McGee applies some final touches to the skin with a heat gun.