In a mixing bowl, whisk together the olive oil, salt, garlic powder, thyme, sage, and black pepper to prepare a mixture for the turkey.

Set up a baking sheet with a rack and pat the turkey dry. Rub the spice mixture thoroughly over the turkey and inside the cavity.

Let the turkey sit at room temperature for about 30 minutes. Meanwhile, adjust your oven rack to the lower third and preheat the oven to 350°F.

Trim the top of the garlic head, drizzle with the remaining olive oil, wrap in foil, and position it on the baking sheet alongside the turkey.

Place the turkey in the oven. Pour the cup of water into the pan, ensuring it’s not directly on the turkey, and roast for about 2 hours and 30 minutes while adding more water as required.

The turkey will be ready when its skin is golden and it reaches an internal temperature of 165°F.

After cooking, let the turkey rest for 30 minutes before carving. Keep the roasted garlic and strain the drippings for the gravy.

Melt the butter in a saucepan over medium heat. Add the flour to create a roux and cook, stirring continuously, until it turns a shade of toffee, approximately 17-20 minutes.

Incorporate the roasted garlic, turkey drippings, sage, and seasoning, whisking until smooth. Gradually mix in the stock, bringing it to a simmer and stirring until it thickens, about 2 minutes.

Adjust seasoning to taste before serving the gravy alongside the carved turkey.