Gather the ingredients. Place a rack in a large roasting pan and preheat the oven to 350 F.
Remove the thawed turkey from its packaging and pat dry with paper towels. Remove the innards and discard them or use them to make homemade stock. Place the turkey on the rack in the roasting pan and sprinkle lightly with salt and pepper. Rub the inside of the cavity with salt and add the carrot, celery, onion, and sprigs of herbs. Tuck the wings under the bird and tie the drumsticks together with kitchen twine.
Melt 6 tablespoons of butter in a saucepan over medium heat. Add the fresh chopped herbs and bring to a simmer.
Brush the turkey with the butter and herb mixture. Place in the oven and roast for 1 hour and 45 minutes. Place a foil tent over the turkey and continue to roast for about 1 to 1 1/2 hours longer, basting every 20 to 30 minutes. The turkey should register about 156 F to 160 F in the breast meat and about 170 in the thigh (make sure the thermometer is in the thickest part of the meat and is not touching bone).
Remove the turkey to a platter and let it rest for 20 to 30 minutes.
While the turkey rests, prepare the gravy. Pour the pan drippings into a gravy separator and let stand for 2 minutes, until the fat rises to the top. Pour the broth into a cup or bowl, leaving the fat in the separator. Set the defatted broth aside and measure 1/2 cup of fat. If you don't have 1/2 cup of fat, add butter to make 1/2 cup. Pour the fat into a saucepan and place it over medium-low heat.
Add the flour to the hot fat and cook the roux, whisking constantly, for 2 minutes.
Whisk in the reserved defatted broth along with 2 cups of chicken stock. Continue to cook, constantly whisking, until the gravy is thickened. Add more stock to thin the gravy, as desired. Taste the gravy and add salt and pepper, as needed.
Strain the gravy, if desired, and pour it into a gravy boat or serving bowl. Serve the gravy with the turkey.