Peel and cut the potatoes. Peel the potatoes to remove all skin. Halve smaller potatoes and quarter larger ones so they cook at the same rate.
Simmer until tender. Place the potatoes in a large pot, cover with cold water by about an inch and add a pinch of salt. Bring to a boil, then reduce to a steady simmer. Cook for 20–30 minutes, until a fork slides through the centre of the largest piece with no resistance.
Drain and let the steam escape. Drain the potatoes well and return them to the hot pot, off the heat. Leave uncovered for a minute, until the excess moisture has steamed off.
Mash and season. Drain the potatoes well and return them to the hot pot, off the heat. Let the steam escape for a minute, then add the butter, warm milk and a pinch of salt. Mash by hand until creamy. Taste and add a splash more milk or a little more salt, as needed.
Taste your potatoes. Adjust by adding more milk for creaminess, more butter for flavour & more salt for enhanced taste.
Serve warm. Spoon into a warm serving bowl. Make a shallow hollow on top, add a little butter and bring straight to the table.