Juiciest Turkey you'll ever cook:
Gravy base:
2 tablespoons (1/4 stick) unsalted butter
2 pounds turkey necks and/or wings
2 cups diced onions
1 cup diced peeled carrots
1 cup diced celery
6 cups (or more) low-salt chicken broth
Turkey ingredients:
1 cup (2 sticks) butter, room temperature, divided
2 teaspoons minced fresh thyme plus 15 fresh thyme sprigs
2 teaspoons minced fresh tarragon plus 5 large fresh tarragon sprigs
2 teaspoons minced fresh rosemary plus 5 fresh rosemary sprigs
2 teaspoons minced fresh sage plus 5 fresh sage sprigs
1 14- to 16-pound turkey
4 cups low-salt chicken broth, divided
1/4 cup all purpose flour
Preparation
For gravy base:
Melt butter in heavy large deep skillet over high heat. Add turkey necks and/or wings and sauté until deep brown, about 15 minutes. Add onions, carrots, and celery and sauté until vegetables are deep brown, about 15 minutes. Add 6 cups chicken broth and bring to boil. Reduce heat to medium-low and simmer uncovered 45 minutes, stirring occasionally.
Pour gravy base through strainer set over 4-cup measuring cup, pressing on solids to extract liquid. If necessary, add enough chicken broth to gravy base to measure 4 cups. (Gravy base can be prepared 2 days ahead. Cool slightly. Refrigerate uncovered until cold, then cover and keep chilled. Rewarm before using.)
For turkey:
Mix 1/2 cup butter and all minced herbs in small bowl; season herb butter with salt and pepper. Transfer 2 generous tablespoons to another small bowl and reserve for gravy; let stand at room temperature.
Set rack at lowest position in oven and preheat to 425°F. Rinse turkey inside and out; pat dry. Starting at neck end, slide hand between skin and breast meat to loosen skin. Rub 4 tablespoons herb butter over breast meat under skin. Place turkey on rack set in large roasting pan. Sprinkle main cavity generously with salt and pepper. Place 4 tablespoons plain butter and all fresh herb sprigs in main cavity. Tuck wing tips under. Tie legs together loosely. Rub remaining herb butter over outside of turkey. Sprinkle turkey generously with salt and pepper.
Place turkey in oven and roast 20 minutes. Reduce oven temperature to 350°F. Roast turkey 30 minutes; pour 1 cup broth over and add 1 tablespoon plain butter to roasting pan. Roast turkey 30 minutes; baste with pan juices, then pour 1 cup broth over and add 1 tablespoon butter to pan. Cover turkey loosely with foil. Roast turkey until thermometer inserted into thickest part of thigh registers 175°F, basting with pan juices and adding 1 cup broth and 1 tablespoon butter to pan every 45 minutes, about 1 hour 45 minutes longer. Transfer turkey to platter; let stand 30 minutes (internal temperature will rise 5 to 10 degrees).
Strain pan juices into bowl; whisk in gravy base. Melt reserved 2 tablespoons herb butter in heavy large saucepan over medium heat; add flour and whisk constantly until roux is golden brown, about 6 minutes. Gradually add pan juice-gravy base mixture; increase heat and whisk constantly until gravy thickens, boils, and is smooth. Reduce heat to medium; boil gently until gravy is reduced to 4 1/2 cups, whisking often, about 10 minutes. Season gravy with salt and pepper.