Season steaks generously on both sides with salt and pepper.
Heat olive oil in a large cast-iron skillet over high heat until the oil reaches its smoke point.
Sear steaks for 4-5 minutes per side for medium-rare, or until an internal temperature of 130°F (54°C) is reached.
Remove steaks from skillet and transfer to a plate; tent loosely with foil to rest for at least 5 minutes.
Reduce skillet heat to medium and add butter.
Add sliced mushrooms and sauté for 5-7 minutes until well-browned and moisture has evaporated.
Stir in shallots and garlic; cook for 60 seconds until fragrant.
Deglaze the skillet with white wine, scraping the fond from the bottom of the pan, and simmer until the liquid is reduced by half.
Whisk in heavy cream and thyme; continue to simmer for 2-3 minutes until the sauce coats the back of a spoon.
Serve the steaks immediately with the mushroom sauce spooned over the top.