Cooking a whole bird isn't as difficult as it sounds. The trick is to brine in advance for really moist, tender meat, and then to spatchcock—or take out the backbone—for even cooking. And unlike the turkey your mother used to roast for an eternity, this one will cook in just about an hour.
For the brine: The day before you plan to roast the turkey, bring 5½ quarts of water, the salt, bay leaves, and thyme to a boil in a large pot over high heat. Reduce the temperature to low and simmer for 5 minutes, then remove the pot from the heat and cool to room temperature. When the brine is cool, submerge the turkey into the brine and refrigerate for 24 hours. After 24 hours, drain the brine and discard and dry the bird well with paper towels.
For the turkey: Preheat the oven to 475 degrees F. To spatchcock the turkey, use kitchen shears to cut through the ribcage along both sides of the backbone. Remove the backbone and discard. This will allow the bird to be splayed open, or butterflied. (To fully spatchcock, you can also remove the breastbone, but we are not going that far with it.) Clip the ends of the wings. Press down on the turkey to create a uniform flatness, then flip it over to prepare for seasoning. Carefully separate the breast meat from the skin by wiggling an upside-down spoon between the skin and the meat. Evenly rub butter underneath skin over the breast meat, taking care not to tear the skin.
Season the entire bird with 1½ teaspoons of kosher salt and place the turkey skin side up onto a lightly buttered baking sheet or a large roasting pan. Place the pan into the oven and cook for 15 minutes, then lower the oven temperature to 375 degrees F and continue cooking for 50-60 minutes or until the turkey reaches an internal temperature of 160 degrees F.
To test for doneness, place the thermometer into the thickest part of the leg and the breast for an internal temperature of 160°F degrees. Remove the pan from oven, and when it’s cool enough to handle, place the turkey onto a large cutting board to rest at room temperature.
For the gravy: Pour the pan drippings into a bowl; return half to the roasting pan. Heat the roasting pan and, using a wooden spoon, scrape up the brown bits on the bottom. Stir 3 tablespoons flour into the pan drippings. Continue to cook until mixture is bubbly and thickened. Whisk in the chicken stock and ½ teaspoon of salt and bring to a boil to thicken, all the while whisking to take out the lumps. Remove from heat and pour into a serving vessel. Set aside.
Carve the turkey: Remove legs by pulling them away from the body and slicing along connection point. Remove any visible tendons. Separate the thigh from the leg. Slice down the middle of the breastbone and pull the wing back on each side, then slice to remove. Separate the wing into two pieces. Remove the breast meat from the bone and cut into thin slices. Arrange onto a serving platter and serve with the gravy drizzled over top.