These are the potatoes that brought Chef Joel Robuchon to world notice, and they are the potatoes that brought Jean Pierre Clot fortune. He is the man who resurrected this potato from the Alps and sent it to Chef Robuchon, who proceeded to make this over-the-top version of mashed potatoes. This version is simplified from Chef Robuchon’s, as it skips using a tamis, or drum sieve, for the potatoes. Do not attempt this in a food processor or blender as it will provide you with gummy, pasty potatoes. You will need a food mill, or a ricer.