Optional: Remove the steaks from refrigerator 30-60 minutes ahead of time for more uniform cooking.
Position the oven rack in the middle and preheat oven to 425°F.
Place a large cast-iron skillet over high heat and allow to heat for 5 minutes until very hot. (You can also place in the preheated oven for 15 minutes.) Use oven mitts!
Pat dry the steaks with paper towels to remove excess moisture that could interfere with searing. Then rub on all sides with 1 tablespoon of the oil before seasoning both sides with salt and pepper.
Add the remaining 1 tablespoon oil to the hot pan and swirl to coat. Using kitchen tongs carefully place the steak in the pan, laying it away from you to avoid splatter.
Sear the first side for 2 minutes. Flip the steaks and sear the other side for 2 minutes more. Optional: sear the edges by holding the steaks vertically and pressing them against the pan until brown.
Add the garlic cloves and rosemary to the pan. Spoon juices onto the meat and transfer the pan to the oven.
Bake for 2-3 minutes before checking doneness using an instant-read thermometer: medium-rare is 130°F and medium 140°F (see recipe notes for other donenesses). If the steaks are not done yet, flip the steaks and continue cooking a few minutes longer.
Remove steaks to a plate or cutting board. Cover with aluminum foil and allow them to rest for 5 minutes so the juices can retreat back into the meat.
Slice the steaks crosswise against the grain to serve.