01 - Pat steaks completely dry with paper towels. Season both sides generously with salt and freshly ground black pepper, pressing the seasoning into the meat.
02 - Heat olive oil and 1 tablespoon butter in a large skillet over medium-high heat until butter foams and pan is hot but not smoking.
03 - Add steaks to the hot skillet and sear for 2–3 minutes per side for medium-rare doneness, or adjust time to reach preferred internal temperature. Transfer steaks to a warm plate and tent loosely with foil to rest.
04 - Reduce heat to medium. Add remaining 2 tablespoons butter to the same skillet. Add sliced mushrooms and sauté for 3–4 minutes until golden brown and edges are crispy.
05 - Add minced shallots and garlic to the mushrooms. Cook for 1–2 minutes until fragrant and shallots are translucent, stirring frequently to prevent burning.
06 - Stir in Worcestershire sauce and Dijon mustard, mixing well to combine with the mushroom mixture and distribute evenly.
07 - Carefully pour in brandy or cognac. For dramatic presentation, flambé by carefully igniting the liquid (stand back and use extreme caution), or simply let it simmer for 1 minute to reduce alcohol content.
08 - Pour in beef broth and simmer for 2 minutes, allowing the liquid to reduce slightly and intensify in flavor while scraping up any browned bits from the pan bottom.
09 - Stir in heavy cream and cook for 2–3 minutes until the sauce thickens enough to coat the back of a spoon, stirring constantly to prevent scorching.
10 - Taste the sauce and adjust seasoning with additional salt and freshly ground black pepper as needed to achieve balanced flavor.
11 - Return steaks and any accumulated juices to the pan. Spoon the mushroom sauce generously over the steaks and simmer gently for 1 minute to warm through. Sprinkle with fresh parsley and serve immediately.