Remove the ribeye steaks from the refrigerator and let them rest at room temperature for about 45 minutes. This helps the meat cook more evenly. Generously season both sides of the steaks with kosher salt and freshly ground black pepper, pressing the seasoning into the surface.

Heat a 12-inch cast iron skillet over medium-high heat. Once the pan is hot and the oil is shimmering, carefully place both steaks in the skillet. Sear for 30 seconds on one side, then flip. Continue flipping the steaks every 30 seconds to promote an even crust, adjusting the heat as needed to avoid scorching.

Once the steaks begin to develop a deep golden crust, add the butter, smashed garlic, and rosemary sprigs to the pan. As the butter melts and foams, tilt the pan slightly and use a spoon to baste the steaks with the herbed butter. Continue flipping and basting until the internal temperature of the steaks is just below your preferred doneness.

For medium-rare, remove the steaks from the pan at around 125°F. They will continue to cook slightly as they rest. Let the steaks rest on a cutting board for about 10 minutes before slicing to allow the juices to redistribute.

For added richness, after resting, return each steak to the skillet for a final sear on the fatty edge. Hold the steak upright with tongs to press the fat side directly against the hot pan for about one minute, just until it's browned and crisp.

Slice, serve, and enjoy while the steaks are hot and perfectly juicy.