Remove the filet mignon from the fridge 30 minutes before cooking to bring it to room temperature.
Pat the steaks dry and season both sides with salt and black pepper.
Heat a cast iron skillet over high heat and add olive oil.
Sear the steaks for 2-3 minutes per side until a golden-brown crust forms.
Reduce the heat to medium-low, add butter, garlic, and fresh herbs, and baste the steaks for 1-2 minutes.
Use a meat thermometer to check doneness: 130°F (54°C) for medium-rare, 140°F (60°C) for medium.
Remove from the skillet and let the steaks rest for 5 minutes before serving.