Preheat the oven to 120°C.
Dry ciabatta, lemon rind, capers, anchovies, onions, and olives on a baking sheet for two hours.
Pulse the dried mixture in a food processor for two minutes to form fine breadcrumbs.
Preheat the oven to 180°C.
Season lamb and sear it in a hot oiled frying pan for two minutes to brown the fat.
Coat seared lamb in Dijon mustard and roll it in the herb breadcrumbs.
Bake the lamb for 12 minutes until medium rare, turning halfway through, then rest.
Increase oven temperature to 190°C.
Peel, seed, and chop butternut squash into even chunks.
Toss squash with garlic, lemon, olive oil, and 70g melted butter.
Roast squash with thyme for 20 minutes until tender.
Blend roasted squash with 30g chilled butter, mustard, and cream until smooth.
Slice lamb into cutlets and serve on a bed of the squash purée.