Step 1: Prepare and season steaks
Pat the steaks dry with paper towels. Season both sides generously with salt and freshly ground black pepper.

Step 2: Cook the steaks
Heat 1 tablespoon of butter in a heavy skillet over medium-high heat. Add the steaks and cook 3-4 minutes per side for medium-rare, or until desired doneness. Remove steaks from the pan and set aside, loosely tented with foil to rest.

Step 3: Sauté the shallots
In the same skillet, reduce heat to medium and add the remaining tablespoon of butter. Add minced shallots and sauté until translucent and fragrant, about 2 minutes.

Step 4: Deglaze the pan
Add the cognac or brandy to the pan. Carefully flambé the sauce by igniting the alcohol with a long lighter or spoon to burn off the alcohol (optional but traditional). Let the flames subside.

Step 5: Add sauces and broth
Stir in the tomato paste, Dijon mustard, Worcestershire sauce, and beef broth. Let the sauce simmer and reduce by half, about 4-5 minutes.

Step 6: Finish the sauce
Reduce heat to low and stir in the heavy cream. Let the sauce thicken slightly, about 2-3 minutes. Taste and adjust seasoning with salt and pepper as needed.

Step 7: Serve
Return the steaks to the skillet to warm briefly in the sauce if desired. Plate the steaks, spoon the sauce generously over them, and sprinkle with finely chopped chives.