Peel the potatoes, chop them coarsely, place in a saucepan, and cover with cold water. After the water boils, add a teaspoon of salt and cook for 10-12 minutes. Check for doneness like this: pierce a piece with a knife; the knife should go in easily, but the potatoes should not fall apart.

Drain the water, add milk to barely cover the potatoes, and return to the heat. As soon as the milk boils, remove from the heat, add a pinch of nutmeg and a piece of butter, and crush with a masher into a puree.