Prepare the Mushroom Sauce:

Heat a large heavy-bottomed pan over medium-high heat. Melt 2 Tbsp of butter and 1 Tbsp of olive oil. Add the sliced mushrooms and cook for 6 minutes, stirring occasionally, until softened and most of the liquid has evaporated.

Add the diced onion and cook for 3 more minutes, stirring often.

Stir in minced garlic, thyme, 1/4 tsp sea salt, and 1/8 tsp black pepper. Continue to cook for 2 more minutes until the garlic is fragrant. Transfer the mushroom mixture to a plate and set aside. Wipe the pan clean with a paper towel.

Cook the Filet Mignon:

Season the steaks with 1 tsp salt and 1/4 tsp black pepper.

Heat the same pan over medium-high heat and add 2 Tbsp butter and 1 Tbsp olive oil. Once the butter has finished foaming, add the steaks and sear them for 3-5 minutes per side for medium-rare, or 5-6 minutes for medium doneness. Turn the steaks once to ensure an even sear.

Once the steaks have reached your desired doneness, transfer them to the plate with the mushrooms.

Make the Sauce:

In the same pan, add 1/2 cup Merlot wine and bring to a boil. Let it reduce by half (about 3 minutes), scraping the bottom of the pan to deglaze and incorporate any browned bits.

Add 1 1/2 cups beef broth and continue boiling until the liquid is reduced to about 2/3 cup (5-7 minutes).

Stir in 1/2 cup heavy cream and let it boil for another 2 minutes until the sauce thickens slightly. Season the sauce to taste with additional salt and pepper if needed.

Combine and Serve:

Add the cooked steaks and mushrooms back into the pan, spooning some of the sauce over the steaks. Let the steaks heat through before removing from heat.

Serve the filet mignon steaks with the creamy mushroom sauce, garnished with fresh thyme sprigs if desired.