Melt butter in large skillet over medium heat. Add chopped garlic, thyme and marjoram; sauté 30 seconds. Add mushrooms; toss to coat with butter. Sprinkle with truffle salt. Cover and cook until mushrooms have released their juices, about 12-13 minutes. Add beef broth, wine, and heavy cream and bring to boil. Cook uncovered until mushrooms are tender and sauce coats mushrooms, about 5 minutes. Season mushroom ragout to taste with truffle salt and pepper. (Ragout can be made 3 hours ahead. Cover skillet and refrigerate.)
Heat heavy medium skillet over high heat until hot. Add peanut oil and tilt skillet to coat evenly. Sprinkle steaks with truffle salt and pepper. Add to skillet and cook to desired doneness, about 4 minutes per side for medium-rare (have a good meat thermometer handy so you cook it exactly to your liking. I linked to the one I use). Transfer steaks to plates. Rewarm mushroom ragout in skillet over medium heat, stirring frequently. Spoon ragout partially over steaks and onto plates. Drizzle mushrooms on each plate with ¼ teaspoon olive oil.
Recipe by Wishes and Dishes at https://wishesndishes.com/filet-mignon-truffled-mushroom-ragout/