An empty bird cooks fastest, but since stuffing is something we eat only once a year, I cut corners to indulge. Rather than sauté the onions and celery, I add them both to the stuffing raw. That way, the stuffing can go straight into the turkey without having to cool down first, and the flavors are much livelier. I use only fresh sage, and lots of it, rather than the other traditional herbs, musty store-bought seasonings, or time sucks like adding the giblets, oysters, or chestnuts that so many recipes insist on. While those are all nice touches in theory, skipping them allows me to get the turkey into the oven faster, and I can move on to fresh cranberry sauce. And the juice that the stuffing absorbs adds plenty of extra flavor.
Like the stuffing, most of the other turkey trimmings can be made faster from scratch than resorting to the supermarket cornucopia of boxed and canned, premade convenience "foods." And unless you want to give thanks to food chemists and agribusiness, you're better off avoiding all the high-fructose corn syrup and/or polysyllabic ingredients in frozen pies and pie crust, canned cranberry sauce, instant or premade mashed potatoes, and other Thanksgiving specials. (It's bad enough to feign enjoyment in your relatives' company. Why settle for artificial ingredients?)
There are several notable exceptions to this: I'm a squash purist, but the precut pieces now available in the produce section save time on peeling and chopping and can be roasted with just a touch of oil (preferably pumpkin seed), salt, pepper, and herbs. Canned sweet potatoes are also socially acceptable as long as the label does not have the skull-and-crossbones of "candied" or "in light syrup." Fresh are best, but if you only need a vehicle for brown sugar and marshmallows, no one will notice the difference. An even better way to disguise their origins is to mash them with thyme and chili powder rather than the usual sweet spices.
For the flash of green on the plate, most choices in the Birds Eye aisle betray their processing. Broccoli, green beans, and especially asparagus never taste as vibrant after the shock of early cooking and deep-freezing. But edamame, the addictive green soybeans, are the greatest thing frozen since the ice cube. Serve them with a little butter or olive oil, and chopped mint or toasted pine nuts or red peppers from a jar, and you'll be spared the leftovers that are inescapable with fresh vegetables that take forever to prep.
Unfortunately, there are no justifiable shortcuts for the other essentials of the meal: Mashed potatoes and gravy are far superior when started from square one. (Instant potatoes are the ultimate crime against cuisine, while the premade ones in the meat case are loaded with xanthan gum and preservatives.) You might be able to save a step by scrubbing thin-skinned tubers like Yukon Golds and dicing them small before boiling and mashing them with the skins on. But, personally, I would rather peel 15 pounds of potatoes than scrub one. Luckily, gravy is just a matter of moving the turkey out of the roasting pan and putting the pan over a couple of burners, whisking in a slurry of about a half-cup of flour to two cups of water, and cooking until a beautiful, brown miracle happens. It would take longer to heat canned gravy.
As for dessert, I believe that pie with a buttery, flaky crust, after all, is like sausage: better left to the pros. But pumpkin is the essential flavor of Thanksgiving, and fortunately the canned kind improves on nature (most of the moisture has been extracted, so desserts are not watery). One trick is to make a fool rather than a pie: Blend equal parts Libby's pumpkin and mascarpone or cream cheese, sweeten it with sugar to taste, add ginger, cinnamon, nutmeg, and cloves, and lighten it with freshly whipped cream to serve chilled in goblets like a mousse. Or, if you have a Donvier or other ice cream maker, mix a cup of canned, spiced pumpkin with a cup of sugar, a pint of cream, and a cup of milk, and churn away. The result is better than anything made by Ben & Jerry. And it takes less time than a drive to the supermarket.