Place the potatoes in a large pot and cover with salted cold water. Bring to a boil. Reduce the heat to medium-high, and cook for 15 to 20 minutes, until the potatoes are tender when pierced with a fork. Drain.

Meanwhile in a small pot, warm the butter and milk over medium-low heat.

Place the potatoes in a large bowl and mash them with a potato masher, adding a little of the warm milk-and-butter mixture as you go. Continue to mash until the lumps are gone. Add just enough of the milk mixture to get a creamy consistency.

Then whip the potatoes with a fork and season with salt and pepper to taste.

You can make the potatoes a little ahead of time and keep them warm in a low oven, well covered, until ready to serve.