Prepare the Steaks:
Remove the steaks from the refrigerator and let them sit at room temperature for about 30 minutes. This helps ensure even cooking.
Pat the steaks dry with paper towels and season generously with salt and freshly ground black pepper on both sides.
Sear the Steaks:
Heat a cast iron skillet or heavy-bottomed pan over high heat until very hot.
Add the olive oil and 2 tablespoons of butter to the skillet.
Once the butter has melted and is sizzling, add the steaks. Sear for about 3-4 minutes on each side for medium-rare, or until they reach your desired level of doneness.
Use tongs to hold the steaks on their sides and sear the edges for about 1-2 minutes.
Remove the steaks from the skillet and transfer them to a plate. Tent with foil and let them rest while you prepare the sauce.
Make the Creamy Garlic Sauce:
In the same skillet, reduce the heat to medium and add the remaining 2 tablespoons of butter.
Add the minced garlic and sauté for about 1 minute until fragrant.
Pour in the heavy cream and beef broth, stirring to combine.
Whisk in the Parmesan cheese and Dijon mustard, and let the sauce simmer for about 5-7 minutes, until it thickens slightly.
Season the sauce with salt and freshly ground black pepper to taste.
Serve the Steaks:
Place the rested steaks on serving plates.
Spoon the creamy garlic sauce over the steaks, letting it cascade down the sides.
Garnish with chopped fresh parsley if desired.