Party Potatoes

Place the potatoes in a large saucepan and add cold water to cover by at least 1 inch. Add a good pinch of salt and bring to a boil. Reduce the heat to medium, partially cover, and cook until the potatoes are very tender, 12 to 15 minutes. Drain the potatoes and return them to the pan over medium heat. Cook, shaking the pan and stirring so the potatoes don't stick, for 1 to 2 minutes, or until the potatoes are floury and have formed a film on the bottom of the pan.

Remove from the heat and break up the potatoes with a handheld mixer on low speed. Gradually drop in 6 tablespoons of the butter and beat until it is absorbed. Refrigerate the remaining 2 tablespoons butter. Gradually add the cream cheese and sour cream, beating well after each addition. Beat in the milk a little at a time. You want the potatoes to be fluffy and light. If they seem to be getting too wet, don't add all the milk. Season with salt and pepper to taste. (If you don't have an electric mixer, use a hand masher to start and then use a wooden spoon to beat in the butter, cream cheese, sour cream, and milk. Beat the milk into the potatoes one third at a time, beating vigorously after each addition.)

Butter a 9-x-13-inch baking dish and spoon the potatoes into it. Smooth the top, then use a spatula or fork to swirl or score the surface to leave little peaks that will brown nicely during baking. Refrigerate, covered tightly with plastic wrap, for up to 2 days before baking.

Preheat the oven to 350 degrees.

Dust the top of the potatoes with paprika. Cut the remaining 2 tablespoons butter into small pieces and scatter them over the top. Bake until the potatoes are heated through and the top is lightly golden, about 1 hour. (Expect it to take only half the time if the potatoes haven't been refrigerated.) Serve hot.