Peel the potatoes, cut them into evenly sized chunks, and place them in a large pot. Cover with cold water and add a good pinch of salt. Starting with cold water helps the potatoes cook evenly.

Bring the pot to a boil, then reduce the heat to a gentle simmer. Cook for about 15–20 minutes, until a knife slides in easily with no resistance. If there is resistance, continue cooking until tender.

Drain the potatoes and return the empty pot to low heat. Add the drained potatoes back to the pot and gently move them around for 1–2 minutes. This helps remove excess moisture so the mash does not become watery.

While the potatoes are still hot, run them through a potato ricer or food mill back into the pot. Avoid using a hand masher or mixer, as this can make the potatoes gluey.

Stir in the cold butter cubes while the potatoes are hot, using a wooden spoon. Mix until the butter melts and the potatoes become smooth and glossy.

Pour in the milk and heavy cream, stirring gently until the potatoes absorb the liquid and reach a silky consistency. Add the liquid gradually to control the texture.

Season with salt and white pepper, taste, and adjust as needed. Just before serving, stir in the chopped chives or green onions for freshness and a bit of crunch.