Sauté mushrooms in port, brandy, and thyme for an extra-flavorful steak dinner.
In skillet, cook first 4 ingredients over medium-high, stirring often, until softened, about 6 minutes. Add port, brandy, and thyme. Cook until slightly reduced, about 1 minute; season. Meanwhile, season steaks. In cast-iron skillet, sear steaks over high, 3 minutes per side for medium-rare. Top steaks with mushrooms.