Lancashire hotpot is a dish of lamb or mutton (usually best end of neck) onion and (optionally) veg, laid in a dish and topped with sliced overlapping potatoes which if dotted with butter will form a lovely crisp crust. It should always be served in the dish it is cooked in, and traditionally would also contain kidney and oysters (which used to be extremely cheap and were used to supplement the more expensive meat)but rarely does nowadays.