Prepare the Garlic Confit: In a small saucepan, combine the peeled garlic cloves and olive oil. Heat over low heat until the garlic is soft and lightly golden, about 30-40 minutes. Remove from heat and let it cool. Once cool, mash the garlic cloves and set aside.

Make the Parsley-Shallot Butter: In a medium bowl, mix the softened butter with the chopped parsley, shallot, and lemon juice. Season with salt and pepper to taste. Transfer the butter mixture onto a piece of plastic wrap and form it into a log. Wrap tightly and refrigerate until firm.

Prepare the Porterhouse Steak: Preheat the oven to 400°F (200°C). Pat the porterhouse steak dry with paper towels and season generously with salt and black pepper. In a large skillet, heat a tablespoon of olive oil over medium-high heat. Sear the steak for about 4-5 minutes on each side until a golden crust forms.

Add the Crust: In a bowl, combine the toasted spring onions, dried oregano, salt, and black pepper. Once the steak is seared, remove it from the skillet and brush the top with the garlic confit. Sprinkle the spring onion and oregano mixture over the garlic-coated side of the steak.

Roast the Steak: Place the steak on a baking sheet and roast in the preheated oven for about 10-15 minutes for medium-rare, or until it reaches your desired doneness. Use a meat thermometer to check the internal temperature (130°F for medium-rare).

Rest and Serve: Once cooked, remove the steak from the oven and let it rest for 10 minutes. Slice the steak and serve with slices of the parsley-shallot butter on top.