Colcannon (Irish mashed potatoes with cabbage and butter)

Steps

1. Peel the potatoes and cut them into uniform pieces, about 2 inches (5 cm). Place them in a large pot, cover with cold water, add the coarse salt, and bring to a boil. Simmer gently for 18 to 20 minutes, until a knife tip pierces them with no resistance.
2. Meanwhile, core the cabbage, strip away the thick ribs, and finely shred the leaves. Melt one-third of the butter meant for the mash in a skillet over medium heat. Add the cabbage with a pinch of salt and a splash of water, cover, and cook for 5 to 6 minutes, stirring occasionally, until tender but still bright green.
3. Finely slice the scallions, both white and green parts. Heat the milk with the scallions in a small saucepan until just simmering, then remove from the heat and let steep for 5 minutes.
4. Drain the potatoes thoroughly, then return them to the warm pot over low heat for 1 minute, shaking gently to cook off any remaining moisture.
5. Mash them with a potato masher or pass them through a food mill, never a food processor or blender, which makes them gummy. Fold in the remaining butter for the mash, then gradually pour in the warm milk and scallions, stirring with a spatula until you have a smooth, creamy texture.
6. Fold in the cabbage until evenly distributed. Season with fine salt and ground white pepper, then taste and adjust the seasoning.
7. Spoon the colcannon into a mound in a warmed serving dish or on individual plates, make a well in the center with the back of a spoon, and drop in the butter for serving: it melts into a golden pool that you dip each forkful into.