Preheat your oven to 300°F (150°C). Slice the top off the head of garlic to expose the cloves. Drizzle with olive oil and wrap in aluminum foil. Place in the oven and roast for about 45-60 minutes, until the cloves are soft and caramelized. Remove and let cool.

In a bowl, combine the softened butter, roasted garlic cloves (squeezed out of their skins), chives, lemon juice, and lemon zest. Mix well until everything is thoroughly combined. Transfer the mixture onto a piece of parchment paper or plastic wrap, shape into a log, and refrigerate until firm.

In a skillet over medium heat, add the olive oil and pearl onions. Sauté until they are golden brown and tender, about 8-10 minutes. Add thyme and season with salt and pepper. Remove from heat and set aside.

Season the sirloin steaks with salt and pepper on both sides. In a large skillet or cast iron pan, heat a bit of oil over high heat until shimmering. Add the steaks and sear for about 4-5 minutes on each side for medium-rare, or until desired doneness. During the last minute of cooking, add the sautéed pearl onions on top of the steaks to warm through.

Remove the steaks from the skillet and let them rest for 5-10 minutes. Slice the steaks and serve topped with the garlic confit and a slice of the chive compound butter.