Season the steak with salt and pepper. Heat a skillet over medium-high heat and add butter. Sear the steak for 3-4 minutes per side for medium rare. Remove the steak and let it rest.
In the same skillet, add shallots and cook until translucent. Add cognac and flambe. When the flames subside, add beef broth and heavy cream. Stir and reduce the sauce until thickened. Serve the steak with the sauce poured over.