Remove the completely thawed turkey from the refrigerator approximately 45 minutes before roasting.
Preheat the oven to 325°F. Position an oven rack in the lower third of the oven.
Remove the turkey from its packaging. Take out the neck and giblets from the cavities and reserve them for gravy or discard them.
Pat the turkey thoroughly dry inside and out with paper towels. Removing excess moisture helps the skin become golden and crisp.
Place the turkey breast side up on a roasting rack inside a large roasting pan. In a small bowl, combine the softened butter, olive oil, rosemary, sage, thyme, garlic, sea salt, and black pepper. Carefully loosen the skin over the turkey breasts by gently sliding your fingers between the skin and meat.
Rub approximately 1/3 of the herb butter underneath the loosened skin directly over the breast meat.
Rub the remaining herb butter generously over the entire outside of the turkey, including the legs and wings.
Place the onion, lemon, rosemary sprigs, thyme sprigs, and sage leaves loosely inside the turkey cavity. Do not pack the cavity tightly.
Tuck the wing tips underneath the turkey to help prevent them from burning. Tie the legs loosely together with kitchen twine if desired.
Pour the broth into the bottom of the roasting pan, taking care not to pour it directly over the turkey.
Transfer the turkey to the oven and roast for approximately 3 to 3 3/4 hours. Begin checking the temperature earlier rather than relying solely on cooking time, since every turkey and oven can cook differently.
If the skin begins to brown too quickly, loosely tent the breast with aluminum foil.
Check the turkey with an instant-read food thermometer inserted into the thickest part of the breast and the innermost part of the thigh without touching bone. The turkey is safely cooked when both areas reach at least 165°F. Carefully remove the turkey from the oven and transfer it to a large cutting board or serving platter. Loosely tent the turkey with foil and allow it to rest for 30 to 45 minutes before carving.
Remove and discard the aromatics from the cavity. Carve the turkey and serve warm with your favorite Thanksgiving side dishes.