When buying the big bird for the big meal, aiming for 1 1/2 pounds of turkey (including bones and all in your calculations) will ensure you have enough for everyone, with some leftovers for sandwiches. This is no big deal for a family of five, but can get a little daunting if you’re feeding a large crowd, like my Catholic family or 17 of your closest friends.
Things become unwieldy once you get into the 20-pound and over range. The big birds can be hard to fit into a standard oven; their extra bulk means they take way longer to defrost (around five days); and they have to spend more time in the oven, thus running the risk of drying out the breast meat, which is already something you have to contend with when roasting a turkey, a thermodynamic nightmare of a bird.
There are a few strategies you can take here. You can either break the bird down so it cooks more evenly (spatchcock it or butcher into completely separate parts); you can buy two smaller turkeys; or you can buy one reasonably sized turkey and extra turkey thighs and drumsticks, which there are never enough of anyway. You can also buy a reasonable turkey and supplement it with a ham, a roast, or a duck.
If you simply must have a big bird
If you really want to serve one large, single bird, you really must spatchcock it. We’ve discussed this at-length (some might say “ad nauseam”) several times, for many years, but the rationale behind spatchcocking boils down to this:
Dark meat—such as legs and thighs—needs to be cooked to at least 165℉ for all that connective tissue to break down, but breast meat dries out if it gets much over 150℉. Traditional roasting leaves the breast more exposed than the legs, which are shielded by the sides of the pan, which is the exact opposite of what you want.
The larger your turkey, the more pronounced and exacerbated these issues become. Twice the body mass does not equal twice the amount of fat and collagen, unfortunately, so those massive breasts are in more danger of drying out than the ones you’d find on a less-endowed bird.
Besides spatchcocking and roasting, sous-vide cooking is another good option, especially if you break the bird down completely and cook the light and dark parts to two different temperatures. (You can even sous-vide the turkey ahead of time, then warm and crisp in the oven just before dinner time.) This blog can walk you through both methods.
The case for two smaller birds, or one bird and extra bird parts
My biggest complaint with the giant turkey approach is that you still, even after all of your hard work, only get two (2) drumsticks, and if you are feeding a crowd large enough to warrant a giant bird, chances are more than two of them would like a drumstick. Buying two, smaller birds doubles your drumstick count, but fitting two birds in your oven isn’t any easier than fitting one giant bird in your oven—unless you spatchcock them and roast them on two different racks (and not all ovens are large enough to accommodate that).
If your oven can’t fit double birds, you can cook the birds two different ways—smoke and roast (or oven smoke), or smoke and sous-vide, or sous-vide and roast—or you could buy one reasonably sized turkey and supplement it with more of your favorite turkey parts. (Another benefit to buying a smaller turkey? It’s easier to find a humanely raised bird.)
Instead of buying two birds, buy one for the whole-turkey purists and then buy a slew of your favorite turkey parts. This means fewer fights about drumsticks, and you can have a little fun with it. If, for instance, you’ve been wanting to confit some dark meat, cure some Renaissance fair-style legs, roast an extra breast, or roll up an all-white-meat roulade, now is the time.
Supplement with a ham (or a different, better bird)
I used to say I hated cooking turkey, but I’m really good at cooking turkey, and I actually love doing things I’m good at. I do, however, still prefer eating other animal proteins most of the time, and have been known to plump up a Turkey Day menu with a non-turkey offering.
Ham is my favorite. A city ham is already cooked, so the only task you have to worry about is warming it up to 130℉, which can be done in a slow cooker, sous vide situation, or in the humble oven.
Then there is a duck, which is small enough to be roasted next to a reasonably sized turkey, but can also be thrown on the grill (and almost ignored) to good results. (Bonus: You’ll render out a lot of duck fat, which you can save and use for your roasted potatoes on Christmas day.)
You can also use this opportunity to supplement with something a little “weird.” You know what I’m talking about—the dish you wish you could make for Thanksgiving, but never do due to the turkey purists in your family. Serve a reasonable amount of turkey, then make a Mississippi roast or Kimchi pork shoulder in your Instant Pot, sous vide a Brisket in mustard and wine, or smoke a lamb shoulder. If you only need a little bit of extra meat, you can roast a few pork tenderloins, or get one of the men in need of a job to grill a some steaks. Men love grilling steaks.