Preheat your oven to 400°F (200°C).

Heat a skillet over medium-high heat and add 1 tablespoon of olive oil. Add the sliced leeks and sauté until charred and caramelized, about 8-10 minutes. Season with salt and pepper. Remove from heat and set aside.

In a food processor, combine the caramelized leeks and kumquats. Pulse until a coarse mixture forms. Season with salt and pepper to taste. Set aside.

Season the filet mignon steaks generously with salt and pepper on both sides. In a large oven-safe skillet, heat the remaining 1 tablespoon of olive oil over high heat. Sear the steaks for 3-4 minutes on each side until a nice crust forms. Top each steak with the leek and kumquat mixture, pressing it gently onto the surface.

Transfer the skillet to the preheated oven and cook for an additional 5-7 minutes for medium-rare, or until desired doneness is achieved. Use a meat thermometer for accuracy (130°F/54°C for medium-rare).

While the steaks are cooking, in a small bowl, combine the softened butter, honey, and chopped rosemary. Mix until well combined.

Once the filet mignon is cooked to your liking, remove it from the oven and let it rest for 5 minutes. Serve each steak topped with a dollop of rosemary-infused honey butter and garnish with fresh rosemary sprigs and optional microgreens.