Starchy potatoes make the fluffiest mash, but Yukon Gold or other all-purpose potatoes do well too. If you like mashed potatoes with the peel, make sure you scrub them well before cooking. If you like them lumpy, mash with a fork or potato masher; if you like them smooth and light, use a food mill or ricer. Just keep them away from mixers, food processors, or blenders, which makes them gummy.
Other keys to keeping mashed potatoes fluffy: Cook them whole if possible; cook them with the peel on if possible (the peels will slip off easily after cooking, or you can eat them of course); and refrain from poking them. All of these steps reduce the tendency of the spuds to absorb water, which makes them heavier.
Once the potatoes are mashed and combined with the milk and butter, they will keep for a little while in a double boiler. For even better control over them for timing a full meal, it's easier to boil the potatoes a little ahead of time and let them sit for an hour or so (see Step 1).
2 pounds starchy or all-purpose potatoes
1 cup milk, plus more if needed
4 tablespoons (1/2 stick) butter
Salt and freshly ground black pepper
1. Peel the potatoes before cooking if you like. If you're in a hurry, cut the larger ones into halves or quarters. Cut or whole, the idea is to have all the pieces about the same size. Put them in a large, deep pot and cover with cold water. Add a large pinch of salt and bring to a boil.
2. Keep the water rolling until the potatoes are done, anywhere from 15 to 30 minutes, depending on the size of the pieces and how tender you want them. The potatoes are done when a skewer or sharp knife inserted into one meets almost no resistance.
3. Drain the potatoes well and let them dry out a bit. If peeling, give them an extra few minutes to cool enough to handle. (The potatoes can be prepared to this point up to an hour in advance; just leave them in a colander to drain and dry out a bit.)
4. While the potatoes are draining, wipe the pot dry and put it back on the stove over medium-low heat. Add the milk and the butter and sprinkle with salt and pepper.
5. When the butter is almost melted, remove the pot from the heat. Rice the potatoes or run them through a food mill set over the pot or add them directly to the milk mixture and mash with a fork or potato masher. Return the pot to the heat and stir constantly with a wooden spoon to reach the desired consistency, adding more milk if necessary. Taste, adjust the seasoning, and serve.
"Smashed" Potatoes. Omit the milk. In Step 3, add the potatoes directly to the melted butter in the pan and mash roughly with a fork or masher, leaving lots of lumps. Stir a few times, adding more butter if you like.
Garlicky Mashed Potatoes. Peel 1 or 2 heads of garlic (or even 3 if you're a fanatic) and boil them along with the potatoes. If you want stronger garlic mash, add a teaspoon or a tablespoon of minced garlic along with the milk and butter.
Buttermilk Mashed Potatoes. Tangy and fresh tasting: Instead of milk, use buttermilk.
Joël Robuchon Mashed Potatoes. Only a famous French chef could get away with suggesting so much butter (if you really want to go overboard, replace some or all of the milk with cream): In Step 2, after you drain the potatoes, put 1/2 pound (2 sticks) of butter in the pot and set it over medium- low heat to melt, taking care not to let it turn brown. Whisk in the milk or cream. Then proceed with the recipe from Step 3.
7 Other Vegetables to Mash Along with Potatoes
Replace up to half of the potatoes with any of the following vegetables. Add them to the potatoes while they boil if you like or cook them separately (roasted vegetables are especially nice) and mash them in later.
1. Cabbage, cut into ribbons or chopped
2. Brussels sprouts, quartered
3. Celeriac, turnips, or rutabagas, peeled and cubed
4. Carrots or parsnips, peeled and sliced
5. Peas (frozen are fine; no need to thaw them first), added during the last 3 minutes of cooking
6. Winter squash, like butternut or pumpkin, peeled, seeded, and cubed
7. Beets, peeled and cubed (they'll turn the mash fuchsia but taste delicious)