Preheat the oven to 160°C.
Grease an ovenproof dish with 25g of butter.
Layer sliced potatoes in the dish with garlic, salt, and pepper.
Pour a mixture of milk and cream over the potatoes and dot with the remaining butter.
Bake covered for 1.5 hours, then uncovered for 30 minutes until golden.
Line buttered dariole moulds with cling film and wilted spinach.
Combine fried bacon, croutons, eggs, cream, and parsley, then pour into the moulds.
Place moulds in a roasting tin filled halfway with boiling water.
Bake at 160°C for 30 minutes until the timbales are set.
Increase oven temperature to 200°C for the lamb.
Season lamb and sear in a hot pan with olive oil.
Mix breadcrumbs with flatleaf parsley, basil, and chives.
Brush the seared lamb with mustard and coat with the herb breadcrumb mixture.
Roast for 12-14 minutes and rest for 5 minutes before carving.
Serve carved lamb with a portion of potatoes, a timbale, and gravy.