Step 1 Cook the potatoes: To boil, in a heavy saucepan cook the potatoes in enough simmering, salted water to cover until fork-tender, 30 to 40 minutes. Check occasionally and add more water if necessary. To steam, place a wire rack on the bottom of a kettle or large saucepan, and add water to just below the level of the rack. Bring the water to boil, add the potatoes, cover tightly and cook until fork-tender, 30 to 45 minutes. If the lid is not tight-fitting, check occasionally to see if more water should be added.
Step 2 Peel the potatoes while they're still hot.
Step 3Use a potato masher, electric mixer or ricer to mash the potatoes.
Step 4Beating with a mixer or wooden spoon, gradually add heated milk, evaporated milk, half-and-half or whipping cream, according to taste, until light and fluffy. Potatoes will be creamier and thinner if more liquid is used. Finish with softened butter to taste. Season to taste with salt and pepper.
Step 5Serve immediately or spoon into a buttered casserole and pour a light film of cream on top. Keep warm in a 250-degree oven, covered with a towel to absorb the steam.