3 pounds small Yukon Gold or Yellow Finn potatoes, scrubbed
2 bunches of scallions, white and tender green, cut into 1/2-inch pieces
2 teaspoons salt
1 1/2 cups mascarpone cheese (about 3/4 pound), at room temperature
1/4 cup finely chopped flat-leaf parsley
Freshly ground white pepper
Instructions
Put the potatoes and scallions in a large saucepan and add enough water to cover by 1 inch. Add the salt, cover and bring to a boil. Reduce the heat and simmer the potatoes until tender when pierced, about 25 minutes.
Drain the potatoes, reserving 1 cup of the cooking water. Return the potatoes to the saucepan and coarsely mash them by hand. Add the mascarpone and parsley; add a little of the cooking water if the potatoes are too stiff. Season with salt and white pepper and serve at once.