Steak Diane is a classic recipe that tops your favorite steak with a sauce made with cream, cognac, shallots, beef stock, dijon mustard, and Worcestershire sauce. It's perfect for special occasions but also quick & easy enough for weeknight dinners.
Heat butter and oil in a large skillet over medium-high heat. Lightly season steaks with salt and pepper, and add to skillet; cook, about 4-5 minutes per side, until browned and cooked to desired doneness. When the steaks are done, move to a plate and tent with foil.
Return the skillet to medium-high heat and sauté the shallots for 1-2 minutes, until softened.
Add the cognac and cook until the cognac is almost evaporated, about 2 minutes, scraping any browned bits from the bottom of the skillet.
Stir in the broth and bring to a boil over high heat. Cook until thickened, about 2-3 minutes.
Stir in the cream and cook for 2 minutes.
Stir in dijon mustard and Worcestershire, and then return steaks and any accumulated juices to skillet; cook, turning in sauce, until warmed through, about 3 minutes.
Transfer steak to serving plates and stir parsley and chives into sauce. Season with salt and pepper to taste. Pour sauce over steaks and serve.