Heat olive oil in a skillet over medium-high heat. Season the filet mignon steaks with salt and black pepper. Once the oil is hot, add the steaks to the skillet.

Cooking the Steaks

Sear the steaks for about 4-5 minutes on each side for medium-rare, adjusting the time based on your desired doneness. In the last minute of cooking, add butter to the skillet and baste the steaks.

Resting the Steaks

Remove the steaks from the skillet and let them rest for 5 minutes before slicing.

Wild Mushroom Sauce

Sautéing the Aromatics

In the same skillet used for the steaks, add minced shallots and garlic. Sauté until translucent.

Cooking the Mushrooms

Add the wild mushrooms and cook until soft. Pour in red wine and let it reduce by half.

Finishing the Sauce

Add beef broth and thyme, and let it simmer until thickened. Season with salt and pepper to taste.

Gratin Dauphinois

Preparing the Dish

Preheat the oven to 375°F (190°C). Grease a baking dish. Layer half of the sliced potatoes at the bottom.

Building Layers

In a bowl, mix heavy cream, minced garlic, salt, pepper, and nutmeg. Pour half of this mixture over the potatoes. Add the remaining potatoes and top with the rest of the cream mixture.

Adding Cheese

Sprinkle grated Gruyere cheese on top.

Baking

Cover with foil and bake for 45 minutes. Remove foil and bake for an additional 15 minutes until golden and bubbly.