For the turkey:

1. 2-3 days before you plan to roast, spatchcock the turkey:
2. Put the turkey on a cutting board, breast-side down. Use poultry shears or heavy-duty kitchen shears to cut along both sides of the backbone.
3. Starting at either the tail or neck end, cut halfway down the spine, as close to the spine as possible, then cut down the opposing side. Turn the turkey around and cut down the other sides.
4. Spread the two sides of the turkey apart and press down to flatten. You will hear some cracks and popping of the cartilage in the breast bone. Turn the turkey breast side up and press again.
5. You can cut off the wing tips, the wing tips and the first joint, or just tuck them under the bird before roasting. The wing tips and first joint make a good addition to the stock for gravy. I’ve left them on because I think it makes for a prettier bird and some people at the table may like to eat the wings.

Make the buttermilk brine:

1. Open a 2 gallon ziplock bag inside a large bowl. Pour in 3 quarts of buttermilk. Stir in salt.

Marinate the turkey:

1. Put the turkey inside the bag. I find it easiest to hold it by the legs and put it in head first, breast facing down. Seal the bag, squeezing out as much air as possible so that the buttermilk is touching all parts of the turkey.
2. Refrigerate for 48 hours, turning every 12 hours to redistribute the buttermilk.

Prepare the turkey for roasting:

1. Remove the turkey from the refrigerator, and place on a baking sheet. Wipe off the excess buttermilk. Get as much off as possible so that it doesn’t burn in the oven.
2. Let the turkey come to room temperature, about 2-3 hours, so that it cooks quickly and evenly.

Place turkey on rack:

1. After you’ve wiped off as much of the buttermilk as you can and the turkey has come to room temperature, put the turkey on a rack on a rimmed baking sheet. Tuck the wings under the breasts if you haven’t trimmed them off.

To roast the turkey:

1. Roast the turkey in the middle of a 400° oven.
2. Roast until an instant-read thermometer inserted into the deepest part of the breast registers 150 degrees and the thickest part of the thigh without touching bone registers 165 degrees, about 80 to 100 minutes, approximately 6 minutes per pound.
3. Rotate the pan occasionally as needed to ensure even browning. Tent any areas that begin to brown too quickly with foil.
4. Remove the turkey from the oven and let rest for 20-30 minutes before carving.
5. Pour off any collected juices and pass them through a fine mesh strainer if you’d like to add them to your gravy. Skim off any excess fat.
6. You can serve the turkey whole and carve it at the table, or carve it up and serve it already sliced.

For the turkey stock:

1. In a Dutch oven, simmer the turkey parts with 2 cups of chicken broth. Let it simmer until all of the liquid evaporates and the trimmings begin to sizzle, about 20 minutes. Continue to cook, stirring frequently, until a brown coating of frond forms over the bottom of the pan, about 2-4 minutes.
2. Add chopped vegetables and sauté for a few minutes until softened. If the frond seems to be darkening too much, add a few spoons of water and scrape the bottom of the pan with a wooden spoon to dissolve it while you continue to sauté the vegetables.
3. Add rest of the stock, along with the parsley sprigs, thyme, and salt. Simmer for 1-2 hours.
4. Strain stock through a fine meshed sieve. You should have about 4 cups of turkey stock. The stock can be refrigerated for up to 2 days.

To make the turkey gravy:

1. In a medium saucepan, melt the butter over medium heat. Add the flour and increase the heat to medium-high, stirring constantly, until the mixture turns a deep golden brown. Whisk in the turkey stock and bring to a simmer. Simmer until thickened, about 5 minutes. Stir in any drippings, if using, and salt and pepper to taste.
2. The gravy can be refrigerated for up to 3 days or frozen. To thaw, reheat gently over low heat. Stir in extra broth to thin as necessary.