Pat the filet mignon steaks dry with paper towels, then generously season both sides with kosher salt and black pepper. Place the seasoned steaks on a wire rack and let them rest at room temperature for 30 to 60 minutes.

While the steaks are resting, slice the baby Bella mushrooms and finely mince the garlic cloves. In a small bowl, combine the all-purpose flour with garlic powder and onion powder, mixing well.

Heat a large skillet over medium heat, adding the unsalted butter and olive oil. Coat each steak in the flour mixture, ensuring even coverage, then carefully place them in the hot skillet. Sear the steaks for 2 to 3 minutes on each side until they develop a rich, golden-brown crust.

In the same skillet, add the sliced mushrooms and sauté for 2 to 3 minutes until they become tender and start to brown. Then, add the minced garlic and thyme, stirring for an additional minute until fragrant.

Pour in the Marsala wine, using a wooden spoon to scrape the bottom of the skillet. Allow the mixture to simmer for 3 to 4 minutes, reducing slightly.

Stir in the beef stock, letting it simmer for another 3 to 4 minutes until the sauce reduces further. Then, add the heavy cream, stirring until well combined.

Plate the filet mignon steaks and generously spoon the creamy mushroom Marsala sauce over the top. Enjoy the rich flavors.