12ozpotatoesuse a floury/starchy variety eg Russet, Maris Piper
4ozcabbagewhite, green, and savoy all work here
½leek
2tablespoonbutteror more as needed
¼cupmilkor more as needed
Instructions
Peel and dice the potatoes then set to boil in a pot of boiling water, lightly salted. Simmer until tender to a knifepoint then drain.
Meanwhile, shred the cabbage and slice the leek in half rings. Warm half of the butter in a small skillet over a medium heat then add the leek. Cook a minute, reducing the heat if needed to avoid the leek burning, then add the cabbage. Cook, stirring now and then, until the cabbage wilts and becomes tender. Savoy will be quicker, but this might take a couple minutes with white/green cabbage.
Add the remaining butter, milk and some salt and pepper to the potatoes and mash. Add some more milk and butter as needed if your potatoes are still a bit dry or if you want them creamier.
Combine the cabbage and mashed potatoes (which you add to which is up to you), mix so everything is reasonably well distributed but try not to over-mix so the potatoes don't lose their lighter texture, then serve.
Notes
Note, if you want to make this with leftovers, you can still saute the leek and cabbage in a skillet, just do so for less time. For the potatoes, I'd suggest re-heating in the microwave and then mash, if not already mashed, with milk and butter as needed. If you have leftover colcannon, you can also re-heat it either in a pot or the microwave with a splash of milk to give it back it's smooth creaminess, or heat in butter more in a similar way to bubble and squeak. You can make one or more "cakes", either just the mixture or with a little added flour, and fry in a skillet/frying pan with some butter - it's tasty this way with slightly crisp edges.