Peel and cut the potatoes into 1 cm (1/2 inch) slices.

Place in pot of cold salted water and put on to boil.

Place cream and milk in small saucepan and slowly warm.

Once the potatoes are boiling, reduce the heat slightly and cook until they start to fall apart in the pot.

Strain well (allow to sit in strainer for 1 minute)

Potatoes can be transferred to a large mixing bowl and mashed, or preferably put through a mouli into a large mixing bowl.

Once all the lumps have been mashed out of the potatoes, turn the cream and milk up to boil (keep an eye on it, as soon as it starts to boil, remove from the heat).

Meanwhile, using a sturdy whisk, whisk the potatoes vigorously with the butter.

Once the cream and milk have boiled, fold some not all, of it into the mash with a rubber spatula.

Whisk the potatoes vigorously once again, and taste for seasoning. If at this stage they are not fluffy a little more cream and milk can be folded and then whisked in.