Preheat the oven to 300°F (150°C). Slice the top off the head of garlic to expose the cloves. Drizzle with olive oil and wrap it in foil. Roast in the oven for about 45 minutes, or until the cloves are soft and caramelized. Let cool, then squeeze the cloves out of their skins into a bowl.

In a separate bowl, combine the softened butter, roasted garlic, chopped parsley, and lemon juice. Mix well until fully combined. Season with salt and pepper to taste. Set aside.

In a skillet over medium heat, heat 2 tablespoons of olive oil. Add the pearl onions and sauté for about 10 minutes until they are golden brown and tender. Remove from heat and stir in the chopped tarragon. Set aside.

Season the flat iron steaks generously with salt and pepper on both sides. Heat a grill or skillet over high heat. Cook the steaks for about 4-5 minutes on each side for medium-rare, or until your desired doneness. Remove from heat and let rest for 5 minutes.

Preheat the oven broiler. Place the cooked steaks on a baking sheet. Top each steak with a generous layer of sautéed pearl onions, then sprinkle breadcrumbs evenly over the top. Broil for 2-3 minutes, or until the breadcrumbs are golden brown and crispy.

Remove the steaks from the oven and let them rest for a minute. Serve topped with the garlic confit and parsley butter.