Remove the steaks from the refrigerator and let them come to room temperature for about 20 minutes before cooking.
Pat the steaks dry with paper towels to remove any moisture.
Season both sides of each steak evenly with kosher salt and freshly ground black pepper.
Heat a large cast-iron skillet or heavy-bottomed pan over high heat until very hot, about 3-5 minutes.
Add the vegetable oil to the pan and swirl to coat.
Carefully place the steaks in the hot pan and sear without moving them for 4 minutes.
Flip the steaks and add the unsalted butter, smashed garlic cloves, and thyme sprigs to the pan.
Tilt the pan slightly and use a spoon to baste the steaks continuously with the melted butter and aromatics for another 4 minutes for medium-rare doneness.
Check the internal temperature with a meat thermometer; it should read 130°F (54°C) for medium-rare.
Remove the steaks from the pan and transfer to a plate. Tent loosely with foil and let rest for 5 minutes to allow the juices to redistribute.
Slice the steak against the grain and serve immediately.