Mashed potatoes with pecorino

Peel the potatoes (or leave the skin on; it stays in the masher).

Put the potatoes in a pot of cold water and boil over high heat.

Check with a fork or toothpick every so often; they are ready when the fork goes through and the potato breaks apart easily but keeps its shape -- not mushy, not firm. There is no set time.

Drain well.

Pass the hot potatoes through the potato masher, scraping off what clings to it.

Working quickly while the potatoes are hot, mix, then add the first 50 g of butter and let it melt.

Add salt to taste, the pecorino and a little splash of hot milk; mix.

Add the rest of the butter and another splash of milk and mix; keep adding milk, up to the whole cup, until creamy and silky, not too runny and not too thick, and the butter has melted.