Serves up to 24
2 fresh turkeys (about 12 pounds each), giblets and neck removed, tail cut off, turkey rinsed and patted dry
1/2 cup kosher salt
6 tablespoons herbes de Provence
1/4 cup finely grated orange zest
3 tablespoons fennel seeds, minced
3 tablespoons ground black pepper
1/4 cup pure olive oil
3 medium-large onions, unpeeled and cut into large chunks
2 large carrots, cut into large chunks
2 celery stalks, cut into large chunks
1 cup dry white wine or vermouth
1/4 cup cornstarch dissolved in 2 tablespoons water
TURKEY PREP: The night before, prepare turkeys as described above. Place turkey #1, breast down, on a work surface and with heavy-duty kitchen shears, cut out the back. Open up turkey and turn it breast up, pressing on it with the palm of your hand so that it lies as flat as possible.
Completely loosen the skin on both turkeys over breast, legs, and thighs. Mix salt, herbes de Provence, zest, fennel, and pepper. Rub spice mixture under the skin of each turkey—over breasts, legs, and thighs, in the cavity of the whole turkey and the back of the butterflied one, and finally over the wings; set each turkey on a platter or pan large enough to hold it. Refrigerate, uncovered, overnight.
BROTH: Meanwhile, hack necks and back into 1 ½ –to 2-inch chunks. Cut, tails, hearts, and gizzards into 1-inch chunks (discard liver). Heat 2 tablespoons of the oil a 5- to 6-quart Dutch oven over medium-high heat. Add one of the onions and cut up turkey pieces to pan; sauté until they lose their raw color, about 5 minutes. Cover pan, reduce heat to low and let onion and turkey parts cook to release flavorful juices, about 20 minutes. Increase heat to medium-high, add 4 cups of water, and bring to a simmer. Reduce heat back to low and simmer, partially covered, to make a flavorful, unsalted broth, 20 to 30 minutes longer. Strain out solids and add enough water to broth to equal 4 cups; return broth to saucepan.
TURKEY #1: Five to 6 hours before serving, adjust oven rack to lower-middle position and heat oven to 425 degrees. Place butterflied turkey, skin side up, on a lipped cookie sheet over a bed of half the chopped onions, carrots, and celery. Roast until a meat thermometer, inserted into the thigh registers about 175, 1 to 1½ hours. Keep an eye on the vegetables and pan drippings throughout the cooking process. They should be kept dry enough to brown and produce caramelized drippings but moist enough to keep from burning, so add water as needed throughout the cooking process. Remove pan from oven; transfer turkey to a cutting board; let rest 30 minutes and up to 1 hour. Reserve vegetables and pan juices for turkey #2. Carve turkey, transferring slices to an oven-proof platter.
TURKEY #2: Adjust oven rack to lowest position and reduce oven temperature to 400 degrees. Scrape vegetable bed and pan drippings from turkey #1 into a heavy-duty roasting pan. Set a V-rack in the roasting pan. Place remaining vegetables in cavity and set turkey, breast side down, on V-rack. Brush turkey back with pan dripping from turkey #1. Roast 1 hour. Remove from oven, close oven door, and baste turkey back and sides with some of the pan drippings. With two wads of paper towels, carefully turn turkey, breast side up and baste with some of the pan drippings. Continue to roast it until a meat thermometer inserted in the leg pit registers 175, 1 to 1 ½ hours longer. Keep an eye on the vegetables and pan drippings throughout the cooking process. They should be kept dry enough to brown and produce the rich brown drippings for gravy, but moist enough to keep from burning, so add water as needed throughout the cooking process. Transfer turkey to a platter, scraping vegetables from cavity into pan.
GRAVY: Set the roasting pan over 2 burners set on medium-high. Add wine and cook, using a wooden spoon or rubber spatula to loosen brown bits. Strain contents of roasting pan, pressing on solids to release flavorful drippings. Reserve drippings; discard solids. Return unsalted chicken broth to a simmer. Tasting as you go, add enough of the pan drippings to make a flavorful, yet not overly salted gravy. Whisk cornstarch into gravy, bring to a boil, reduce heat to low, and simmer until sauce thickens. Pour gravy into a serving bowl or boat and serve immediately.