Peel and cut the Waxy Potatoes into even 1–2 inch chunks; place them in a pot and cover with cold water, then add a generous pinch of Coarse Sea Salt.
Bring to a gentle boil, then reduce to a simmer and cook until the potatoes are very tender when pierced with a fork, about 15–20 minutes.
Drain the potatoes thoroughly in a colander and return them to the hot pot off the heat for 1–2 minutes to let excess moisture evaporate, stirring once or twice.
Pass the potatoes through a ricer or mash very finely until smooth; avoid overworking if using a regular masher to prevent gluey texture.
Gently warm the Whole Milk with the Unsalted Butter until the butter is melted and the milk is hot but not boiling, then gradually stir this mixture into the potatoes until you reach a creamy, light consistency.
Season to taste with Fine Sea Salt and a little White Pepper; taste and adjust seasoning, then serve immediately with an optional extra pat of butter on top.
