Rumplethumps are a potato side dish. They are a Scottish take on Irish champ and colcannon.
It is made from mashed potato, mixed with onion, some grated cheese, and either shredded cabbage or shredded kale.
The onions are simmered in milk, which is then used to make the mash with. The cabbage or kale is parboiled for a few minutes in water, then drained, and mixed into the mash along with some grated cheese. Fancier versions add some mustard to the mash.
It is then put in an ovenproof dish, then popped under the broiler (aka grill in the UK) for a few minutes to heat all through and brown the top a bit.
