Step 1: Thaw turkey if frozen. Remove giblets and neck from turkey cavities. Pat turkey thoroughly dry, inside and out, with paper towels. Place turkey on a rack in a large roasting pan.
Step 2: Prepare the stuffing: In a large skillet, melt 2 tablespoons of the softened butter over medium heat. Add chopped onions and celery; cook until softened, about 8-10 minutes. Add minced garlic and cook for 1 minute more until fragrant. Remove from heat.
Step 3: In a very large bowl, combine the bread cubes, cooked onion-celery mixture, parsley, sage, thyme, dried rosemary, 1 teaspoon salt, and 1/2 teaspoon pepper. Pour in 1 1/2 cups chicken or vegetable broth and mix gently until bread is moistened. Add more broth if needed for desired consistency, but do not make it soggy. Let the stuffing cool completely.
Step 4: Preheat oven to 425°F (220°C). Loosely stuff the neck and main cavity of the turkey with the cooled stuffing (approximately ¾ cup of stuffing per pound of turkey). Do not pack tightly, as stuffing expands during cooking. If you have extra stuffing, bake it in a separate casserole dish.
Step 5: Rub the remaining softened butter evenly all over the turkey skin, including under the skin of the breast meat. Season generously with salt and freshly ground black pepper. Tuck the wing tips under the turkey and tie the legs together with kitchen twine.
Step 6: Place the turkey in the preheated oven and roast at 425°F (220°C) for 30 minutes. Then, reduce the oven temperature to 325°F (160°C). Continue roasting, basting every 30-45 minutes with pan juices, melted butter, or additional broth. If the skin begins to brown too quickly, loosely tent the turkey with aluminum foil.
Step 7: Continue roasting until a meat thermometer inserted into the thickest part of the thigh (without touching bone) registers 175°F (80°C) and the center of the stuffing reaches 165°F (74°C). Cooking time will vary depending on the size of the turkey, typically 3-3.5 hours for a 12-14 lb turkey.
Step 8: Once cooked, remove the turkey from the oven and transfer it to a large cutting board. Loosely tent with foil and let it rest for at least 20-30 minutes before carving. This allows the juices to redistribute, ensuring a tender and moist oven roasted stuffed turkey. Remove the stuffing from the cavities before carving the turkey.