Makes 10 servings
3 pounds Yukon Gold potatoes, peeled and cut into 2-inch chunks
1 cup milk, hot but not boiling
1/2 pound unsalted butter
Salt and white pepper, to taste
3 egg yolks
1. For potato puree: Warm oven to 300 degrees. Add potatoes to large pot of cold, salted water. Bring to a boil and cook until just tender, about 8-10 minutes. Potatoes should just break apart against side of the pot when pressed with a wooden spoon.
2. Drain and place potatoes on sheet tray, then place in warmed oven for 5 minutes to allow excess liquid to evaporate (this allows potatoes to absorb more milk and butter). Pass potatoes through a ricer or food mill.
3. Melt butter into milk, then add to potatoes, and season with salt and pepper. Once mixture is warm, but no longer hot, add yolks, blend well, and reserve. Can be done up to a day in advance. If doing ahead, be sure to bring potatoes to room temperature for about 30 minutes before finishing, stirring with a spatula to soften.
4. To finish: Preheat oven to 375 degrees. Put potatoes into a piping bag fitted with a star tip. Pipe onto a nonstick baking sheet (or a standard pan lined with buttered parchment paper), swirling potatoes like a soft-serve ice cream cone.
5. Bake in oven for 12-15 minutes, or until nicely browned.