Preheat your oven to 375°F (190°C).

In a baking dish, toss the peeled Cipollini onions with 2 tablespoons of olive oil, salt, and pepper. Spread them out in a single layer and roast in the preheated oven for about 25-30 minutes, or until they are tender and caramelized. Stir halfway through for even cooking.

While the onions are roasting, prepare the Tomahawk steak. Pat the steak dry with paper towels, then rub it all over with the remaining 2 tablespoons of olive oil. Season generously with salt and freshly ground black pepper.

In a small bowl, combine the zest of the bitter oranges, chopped rosemary, and chili flakes. Press this mixture firmly onto the steak, ensuring it adheres well.

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

Transfer the seared steak to the oven alongside the Cipollini onions. Roast for about 30-40 minutes for medium-rare, or until the desired doneness is reached. Use a meat thermometer to check the internal temperature (130°F for medium-rare, 140°F for medium).

While the steak is cooking, in a small bowl, mix the softened butter, honey, and a pinch of salt. Stir in the rosemary and set aside.

Once the steak has reached the desired doneness, remove it from the oven and let it rest for at least 10-15 minutes. This allows the juices to redistribute.

Slice the Tomahawk steak and serve it on a platter alongside the roasted Cipollini onions. Drizzle the rosemary-infused chili honey butter over the steak or serve it on the side. Garnish with fresh rosemary sprigs if desired.