Lamb noisettes is a term used in both the UK and in North America for boneless lamb chops cut from boned, rolled loin from a rack or saddle of lamb.
You can also think of lamb noisettes as lamb T-bone chops with the T-bone removed. They have in them a bit of tenderloin and a bit of eye of loin (which is next to the tenderloin.) They will be about 5 cm (2 inches) thick, though North American cut ones tend to be larger.
Good butchers will sell them with a ring of fat around them. This protects them as they cook, in the same way that filet mignon is often cooked with bacon wrapped around it.
Depending on how thick they are cut, they will weigh anywhere from 40 g to 90 g (1 1/2 to 3 oz).
Allow 2 per person as they are quite small.
Use for dry-heat cooking: pan-frying, broiling (aka grilling in the UK) or grilling (aka BBQ outside the US).
Cook 10 to 12 minutes, turning once half way through.