Preheat your oven to 400°F (200°C).

Toss the fennel wedges with 1 tablespoon of olive oil, salt, and pepper. Spread them out on a baking sheet and roast in the oven for about 25-30 minutes, or until tender and caramelized.

In a skillet, heat 1 tablespoon of olive oil over medium heat. Add the sliced leeks and sauté until they are soft and golden brown, about 5-7 minutes. Remove from the heat and set aside.

Season the filet mignon steaks generously with salt and pepper. In a large oven-safe skillet, heat the remaining tablespoon of olive oil over high heat. Sear the steaks for 2-3 minutes on each side until browned.

In a bowl, combine the sautéed leeks, panko breadcrumbs, and chopped tarragon. Press this mixture onto the top of each seared filet mignon.

Transfer the skillet with the crusted filets to the oven and bake for about 8-10 minutes for medium-rare, or until they reach your desired level of doneness.

In a saucepan, melt the butter over medium heat. Add the minced garlic and sauté for 1 minute until fragrant. Pour in the heavy cream, lemon juice, and lemon zest, stirring to combine. Simmer for 5-7 minutes until the sauce thickens slightly. Add salt and pepper to taste.

Remove the filet mignon from the oven and let rest for a few minutes. Plate the roasted fennel alongside the steaks and drizzle the creamy lemon-tarragon reduction over the top.