In a skillet over medium heat, melt 1 tablespoon of the butter. Add the chopped mushrooms and cook, stirring occasionally, until they are caramelized and most of the moisture has evaporated (about 5-7 minutes). Stir in the minced garlic and cook for an additional 1-2 minutes until fragrant. Remove from heat and let the mushroom mixture cool slightly.

In a bowl, combine the softened butter, caramelized mushrooms, chopped parsley, fresh thyme, salt, and pepper. Mix until well combined. Transfer the mixture to a piece of plastic wrap, shape it into a log, and refrigerate until firm.

Preheat your oven to 400°F (200°C). Season each filet mignon generously with salt and pepper. In a shallow dish, mix the toasted chopped cashews and chili flakes.

Press each filet mignon into the cashew mixture, coating all sides well. Heat olive oil in a large oven-safe skillet over medium-high heat. Once hot, carefully add the coated filet mignon steaks. Sear the steaks for about 2-3 minutes on each side until a crust forms.

Transfer the skillet to the preheated oven and cook for an additional 5-10 minutes, depending on your desired doneness (5 minutes for medium-rare, 7 minutes for medium).

Once cooked to your liking, remove the skillet from the oven and let the steaks rest for a few minutes. Slice the caramelized mushroom compound butter into rounds and place a piece on each filet mignon just before serving.

Enjoy your toasted cashew and chili flake-crusted filet mignon with the deliciously rich and flavorful mushroom butter!