Preheat oven to 190°C/Gas mark 5
Peel, remove the top and bottom of the shallots and finely chop.
Heat a large frying pan and dry fry the lamb on all sides to seal before placing in a roasting tin.
Add the oil, butter and shallots to the same frying pan and gently fry the shallots for 2 minutes.
Add the breadcrumbs and rosemary, stir and fry for a further 2 minutes.
Brush the lamb with the Dijon mustard.
Spoon the breadcrumb mixture on top of the lamb.
Cook the lamb for 40-45 minutes.
Remove from the oven and leave to rest for 10 minutes.
Slice the lamb into cutlets to serve.