Bring the potatoes to the boil, leave them unpeeled. Boil until done. Peel while still warm.

Mash the potatoes and put it back into the pan under low heat. Stirr with a wooden spoon a few minutes to dry the potatoes.

Heat the milk. Add the cubes of butter into the potatoes mixture and keep stirring firmly. When the potatoes stop taking the butter you add the warm milk, bit by bit.

Now change from tool: take the whisk and add the remaining part of the butter. Bring to the taste with salt and pepper,