In a mixing bowl, combine the softened butter, roasted garlic, lemon zest, parsley, and lemon juice. Mix until well combined. Shape the butter into a log using plastic wrap, twisting the ends to seal. Refrigerate until firm.

Remove the ribeye steaks from the refrigerator and allow them to come to room temperature for about 30 minutes. Preheat your oven to 400°F (200°C). Season both sides of the steaks generously with salt and black pepper.

Heat the olive oil in a large oven-safe skillet over medium-high heat. Once hot, add the ribeye steaks and sear for 4-5 minutes on each side, or until a deep brown crust forms.

Add the pearl onions and chopped thyme to the skillet around the steaks during the last minute of searing. Carefully transfer the skillet to the preheated oven and roast for an additional 5-10 minutes, depending on your desired doneness (5 minutes for rare, 7 minutes for medium-rare, and 10 minutes for medium).

Remove the skillet from the oven and transfer the steaks to a cutting board. Let the steaks rest for 5 minutes to allow the juices to redistribute.

Slice the ribeye steaks against the grain and serve topped with the toasted pearl onions and a generous slice of the lemon-zest compound butter.