Instructions

• Remove the steaks from the refrigerator 60 minutes before cooking so they come to room temperature. Pat the steaks dry with paper towels. Generously season all sides with coarsely ground salt and pepper, pressing the seasoning into the meat.
• Place a cast-iron skillet over high heat and let it get very hot. Add 1 tablespoon vegetable oil. When the oil just starts to smoke, reduce the heat to medium-high and add the steaks to the pan without crowding.
• Cook the steaks undisturbed for 4 minutes. After 4 minutes, add 3 tablespoons unsalted butter, 1 sprig of rosemary (optional), and the 3 whole peeled garlic cloves to the skillet.
• Flip the steaks with tongs (do not pierce with a fork). After flipping, tilt the pan slightly and spoon the melted butter, garlic and rosemary juices over the tops of the steaks (baste) for the remaining 4 minutes of this initial cook.
• After a total of about 8 minutes of cooking (4 minutes per side), check the internal temperature with an instant-read thermometer. Because the steaks will continue to cook while resting, remove them when the thermometer reads about 5°F below your desired final doneness. Example final target temps after resting: Medium Rare ~135°F, Medium ~145°F, Medium Well ~155°F.
• If the steaks need more time to reach your target, reduce the heat to medium and continue cooking, flipping once more and continuing to baste, about 3–7 more minutes depending on thickness and desired doneness. Recheck temperature as needed.
• Transfer the steaks to a cutting board. Spoon any accumulated butter from the pan over the steaks one more time, loosely tent them with foil, and let rest at least 10 minutes before slicing. Slice against the grain when ready to serve.
• While the steaks rest, make the sauce: Remove the rosemary sprig and the whole garlic cloves from the skillet. Pour off all but about 1 tablespoon of the fat/juices from the pan.
• Return the skillet to medium-high heat. Add 2 tablespoons minced shallot and sauté about 1 minute until softened. Add 1 minced garlic clove and sauté about 30 seconds more, stirring so it does not burn.
• Add 1/2 cup low-sodium chicken broth and simmer, stirring occasionally, about 3 minutes until the liquid reduces to roughly 1/4 cup.
• Stir in 1/2 cup heavy cream, 1 tablespoon balsamic vinegar, and 1 teaspoon Dijon mustard. Simmer until the sauce is slightly thickened, about 2 minutes.
• Remove the skillet from the heat. Stir in 1 tablespoon unsalted butter until melted, then stir in 1 1/2 tablespoons chopped fresh chives and 1 1/2 tablespoons chopped fresh parsley. Taste and add salt and pepper to taste if desired.
• Pour the sauce over the sliced steaks or serve it on the side.