First Step: Preparation and Ingredient Gathering: Start by removing filet mignon steaks from the refrigerator and allowing them to come to room temperature for 30 to 60 minutes this ensures even cooking. Meanwhile, prepare your garlic herb butter by mixing softened butter with minced garlic, fresh rosemary, and thyme. Shape into a log using plastic wrap and refrigerate until ready to use.

Second Step: Preheat and Season: Preheat your oven to 400–410°F (204–210°C). Season both sides of the filet mignon generously with kosher salt and freshly ground black pepper just before searing. For an extra tender crust, you can salt steaks 2 hours to 2 days in advance and refrigerate uncovered to dry the surface.

Third Step: Sear the Steaks: Heat a cast-iron or oven-safe skillet over medium-high heat. Add olive oil and 3 tablespoons butter. When the butter is foaming and beginning to brown with a nutty aroma, add the steaks. Sear without moving for about 2 minutes on one side, then flip and sear another 2 minutes. Flip once more briefly to promote even heat distribution just before transferring to the oven.

Fourth Step: Roast in the Oven: Transfer the skillet with steaks to the preheated oven and bake for 7 to 12 minutes, depending on thickness and desired doneness:
– Rare: 120-125°F (49-52°C)
– Medium rare: 130-135°F (54-57°C)
– Medium: 140-145°F (60-63°C)
– Medium well: 150-155°F (66-68°C)
– Well done: 160-165°F (71-74°C)
Flip steaks halfway through cooking for even results. Use a meat thermometer for precise temperature checking.

Final Step: Rest and Serve: Remove skillet from the oven and place two slices of garlic herb butter on each steak. Tent loosely with foil and rest for 3 to 5 minutes to allow juices to redistribute and internal temperature to rise slightly. Plate the steaks, garnish with fresh chopped parsley, and drizzle any pan juices over the top before serving immediately.