How to make pomme purée
Find the full recipe here:
https://www.greatbritishchefs.com/how-to-cook/how-to-make-pomme-puree

Pomme purée is basically mashed potatoes given the classical French treatment, but that short description doesn't really do this side dish (made popular by the late great French chef Joël Robuchon) justice. Irresistibly silky and deeply decadent, it gains its smooth texture thanks to a generous amount of butter stirred into the flesh of the potatoes, which is then loosened with a little milk. While mashed potato is rough and ready, easy to knock up and good at absorbing other sauces, pomme purée is made in a gentler way, gradually beating and folding the butter into the potatoes until they become a single, smooth entity that should sit alongside something equally luxurious.