In a skillet, brown lamb loin chops in oil over medium-high, 6 minutes. Turn chops; add thawed artichoke hearts, rosemary sprigs and crushed garlic. Season; cook 6 minutes. Stir artichokes, then reduce heat to medium-low and cook to desired doneness, 6 to 8 minutes for medium-rare. Add a dab of butter; stir to coat artichokes.