Preheat your oven to 375°F (190°C).

Slice the top off the head of garlic, drizzle with olive oil, wrap in aluminum foil, and roast in the preheated oven for about 30-35 minutes, until soft and caramelized. Allow to cool slightly, then squeeze the garlic cloves out of their skins into a bowl.

In a bowl, combine the roasted garlic, chopped marjoram, salt, and black pepper. Mash together with a fork until it forms a paste.

Rub the Tomahawk steak generously with olive oil, then pat the garlic-marjoram paste all over the meat, ensuring an even coating.

Heat a large cast-iron skillet over high heat. Once hot, add the steak and sear for 3-4 minutes on each side until a golden-brown crust forms.

Transfer the skillet to the preheated oven and roast the steak for about 30-40 minutes, or until it reaches your desired level of doneness (135°F for medium-rare). Use a meat thermometer for accuracy.

In a small bowl, combine the softened butter, crushed long peppercorns, and black truffle oil. Mix until well combined.

Once done, remove the steak from the oven and let it rest for 10-15 minutes to allow the juices to redistribute.

Slice the Tomahawk steak against the grain, and serve topped with dollops of truffle butter and garnished with fresh marjoram sprigs.