Remove steaks from the refrigerator 30 minutes before cooking. Pat dry with paper towels and season generously on both sides with salt and pepper.
Heat a large cast-iron skillet over medium-high heat. Once the pan is smoking hot, add the olive oil.
Place the steaks in the skillet and sear for 3 to 4 minutes per side for medium-rare, or until your desired doneness is reached. During the last minute of cooking, add the butter to the pan and baste the meat.
Transfer the steaks to a cutting board and let them rest for at least 5 minutes. Do not wipe out the skillet.
Reduce the skillet heat to medium-low. Add the minced garlic to the remaining pan drippings and cook for 30 seconds until fragrant.
Pour in the beef broth, scraping up any browned bits from the bottom of the pan. Whisk in the heavy cream and Dijon mustard. Simmer for 3 to 4 minutes until the sauce thickens and coats the back of a spoon.
Slice the rested steaks against the grain. Plate the meat, pour the warm garlic sauce over the top, and garnish with chopped parsley.