Remove steaks from refrigerator 60 minutes before cooking to bring to room temperature.
Pat steaks dry with paper towels. GENEROUSLY season steaks on all sides with freshly cracked salt and pepper, pressing salt and pepper into steaks so it sticks.
Heat CAST IRON SKILLET over high heat. Add vegetable oil. When it starts to smoke, reduce heat to medium-high and add steaks. Cook for 4 minutes without moving (SET TIMER). Add butter, garlic and rosemary. Flip steaks with tongs (NOT a fork, you don’t want to pierce your steak), and continue to cook for 4 more minutes. MEANWHILE…
Right after you flip the steaks, spoon melted butter over the steaks. Continue to baste steaks for the remaining cooking time, tilting the pan as needed to spoon the butter.
Check the internal temperature of the steaks after they have cooked a total of 8 minutes (they should be medium rare at this point). You want the temperature to register 5°F lower than the desired doneness (steaks will continue to cook after removing from skillet): For Medium Rare: 130°-140°, Medium: 140°-145°, Medium Well: 150°-160°.
If you wish to continue to cook your steaks, reduce heat to medium and continue to cook steaks to desired temperature, about 3-7 more minutes, flipping one more time and continuing to baste.
Transfer steaks to cutting board, and baste one more time. Loosely tent with foil. Let rest at least 10 minutes before slicing against the grain.