Take steaks out of the fridge and season with salt, pepper and garlic. Set aside to warm up on counter while you cook the sauce.
Cook steaks, and your side dish of choice.
Melt 2 tablespoons of butter in a large pan over medium high heat. Add the mushrooms and season with salt and pepper to taste.
Cook for 5-7 minutes or until mushrooms have softened and are browned. Add the garlic and cook for 30 seconds. Stir in the flour.
Slowly whisk in the beef broth, and Worcestershire sauce. Bring to a simmer and cook until just thickened. Stir in the remaining 2 tablespoons of butter until melted.
Sprinkle with rosemary, then spoon the sauce over steak.
Serve with a side of potatoes and/or veggies