Bring a pan to the smoking point by turning the heat up slowly.
Pat the steaks dry and season with salt & pepper. Drizzle olive oil over the steak.
Lay the steaks away from you, oil side down. Fry for approximately 3 minutes on either side, depending on size and level of doneness. See notes above.
Add the butter and rosemary for the final minute of cooking and baste the steaks continuously. Brush the steaks with the rosemary sprigs. Using tongs, grip the steaks, seal the edges, or tilt the pan using foaming butter to finish the edges.
Once the steaks are sealed, remove them from the pan and leave to rest in a warm place. Spoon the hot butter, garlic, and rosemary over the steak.