Begin by drying the filet mignon thoroughly with paper towels, then generously season each side with kosher salt and black pepper. Place the seasoned steaks on a wire rack and allow them to rest at room temperature for 30 minutes.

While the steaks rest, wash and slice the baby Bella mushrooms into even pieces, aiming for about ¼ inch thickness. Mince the garlic cloves finely.

In a shallow dish, combine the all-purpose flour, garlic powder, and onion powder. Coat the rested steaks evenly in the flour mixture.

Heat a large skillet over medium-high heat, add the unsalted butter and olive oil. Sear the coated steaks for 2-3 minutes on each side until golden brown.

In the same skillet, add the prepared mushrooms and sauté for 2-3 minutes. Then, add the minced garlic and fresh thyme, cooking for an additional minute.

Deglaze the skillet by pouring in the Marsala wine, allowing it to simmer for 3-4 minutes. Then add the beef stock and stir in the heavy cream.

Return the seared steaks to the skillet, simmer for 3-5 minutes until they reach desired doneness, ensuring they are coated in the creamy sauce.

Plate the tender steaks, spooning the rich mushroom sauce over the top. Serve whole or sliced.