Put the potatoes in a large pot, cover with water, and add the salt. Bring the water to a boil and cook until the potatoes are very soft and starting to fall apart, 20 to 30 minutes. Drain the potatoes well, return them to the pot, and mash with a potato masher, a fork, or a sturdy whisk (or use a food mill), adding the cream and butter a little at a time as you mash. Make the potatoes as lumpy or as smooth as you like, but don't keep mashing once they're smooth or they may become gluey. Season to taste with salt and pepper.
Start with very well cooked potatoes. Don't be afraid to go a little overboard—the potatoes should fall apart. Be sure to drain them well.
Add cream and butter slowly as you mash. Lucia Watson likes a hand masher, but a food mill is fine, too.
nutrition information (per serving):
based on eight servings;
Photo: Martha Holmberg