Place the lamb chops in the hot pan in a single layer without crowding. You should hear a good sizzle when they hit the skillet. Do not move them for the first 2–3 minutes so a deep brown crust can form.
Flip the chops and sear the second side for another 2–4 minutes, depending on thickness and how done you like them. For juicy pink centers (medium-rare), aim for an internal temperature of about 130–135°F; for medium, 135–140°F.
As they cook, spoon some of the garlicky rosemary oil and pan juices over the tops of the chops for extra flavor. The garlic will soften and turn lightly golden in the oil—watch closely so it doesn’t burn.
Transfer the lamb chops to a warm plate and pour any remaining pan juices over the top. Let them rest for 5 minutes so the juices redistribute and the meat stays incredibly tender.