Arrange lamb chops on a rimmed baking sheet. Generously season with salt and pepper on both sides and drizzle with olive oil.
Rub garlic and rosemary over chops incorporating with the olive oil, until evenly covered. Cover the pan with plastic wrap or transfer to a container or zip-type bag and refrigerate 4 to 6 hours.
Light a charcoal grill and once the coals are hot, spread on only one side of the grill to allow for an indirect cooking zone on the other side. If using a gas grill, light all the burners and heat grill to 450 degrees. Reduce heat to low before placing lamb on grill.
Place lamb directly over hot coals, cover with the lid and cook for 2 minutes. Remove lid and turn the chops, cooking on each side for about 2 minutes to sear each side. Cover with lid after turning each time.
Grill lamb until medium-rare, 8 to 10 minutes total, depending on size. Once browned on all sides, check internal temperature.
If the thickest part of the meat is within 5 degrees of medium-rare temp, rotate to the indirect heat zone. If using a gas grill, simply turn off one of the burners to create an indirect heat zone.
The chops should have an internal temperature in the thickest part of the meat of 125-130° for medium-rare, 135° for medium.
Once done, remove chops from grill, tent with foil, and allow to rest for 10-15 minutes. Serve with Béarnaise Sauce.
Total Time includes marinating, cooking and resting the meat.