Prepare the Garlic Confit: Preheat your oven to 300°F (150°C). Slice the top off the head of garlic to expose the cloves. Drizzle olive oil over the exposed cloves and sprinkle with sea salt. Wrap the garlic head in aluminum foil and place it in the oven. Roast for about 1 hour or until the cloves are soft and caramelized. Once done, let it cool slightly, then squeeze the roasted garlic cloves into a bowl. Mash them with a fork until smooth. In a separate bowl, combine the softened butter with the mashed garlic. Mix until well combined. If desired, stir in fresh herbs. Transfer the garlic confit butter to a piece of parchment paper, shape it into a log, and refrigerate until firm.

Prepare the Prime Rib: Remove the prime rib from the refrigerator and let it sit at room temperature for about 1 hour. Preheat your oven to 450°F (230°C). In a small bowl, combine the nigella seeds, cracked black pepper, kosher salt, garlic powder, onion powder, chopped rosemary, and chopped thyme. Rub the prime rib all over with olive oil, then coat it generously with the spice mixture. Ensure it's evenly covered on all sides. Place the seasoned prime rib on a roasting rack in a roasting pan, bone side down.

Roast the Prime Rib: Roast in the preheated oven for 20 minutes. This will create a nice crust. After 20 minutes, reduce the oven temperature to 325°F (160°C) and continue roasting until the internal temperature reaches your desired doneness (about 130°F (54°C) for medium-rare). This may take anywhere from 1.5 to 2.5 hours depending on the size of the roast. Once reached, remove the prime rib from the oven and tent it loosely with foil. Let it rest for at least 20 minutes to allow the juices to redistribute.

Serve: Slice the prime rib into thick slices and serve with dollops of roasted garlic confit butter on top. Garnish with additional fresh herbs if desired.