Preparation

• Preheat the oven to 350 degrees. Fill a rimmed baking sheet with a layer of rock salt.
• Prick the potatoes all over with a knife and place them on the salt. Roast about 1 hour, until easily pierced with a knife. Let sit until cool enough to handle.
• Slice the potatoes in half lengthwise and scoop out the flesh, discarding the skins. Run the potato through a food mill with the smallest plate attached. You should have 1½ pounds milled potato.
• Combine the potatoes and flour on a floured work surface, forming a well in the center. Pour the eggs and salt in the well, then use well-floured fingers and a bench scraper to lightly fold the mixture together about 10 times, until just combined.
• Divide the dough into 4 equal portions and sprinkle each with flour. Working with 1 portion at a time, roll the dough into a ¾-inch thick rope. Slice into 1-inch pieces and place on a flour-dusted cookie sheet. Repeat with the remaining portions. If desired, roll the gnocchi gently over the tines of a fork to form small ridges. Refrigerate until ready to cook.
• Bring a large pot of salted water to a boil. Meanwhile, in a large saute pan over low heat, melt 1 tablespoon butter and keep warm.
• Gently place half the gnocchi into the boiling water and cook until they float, about 30 seconds, plus 10 seconds more. Remove and add to the saute pan.
• Add 1 tablespoon cooking water to the saute pan and raise the heat to medium. Gently shake the pan to emulsify the butter and water and glaze the gnocchi with the sauce. Pour into a serving dish. Repeat with the second half of the gnocchi.
• Season with a pinch of salt, top with shaved truffle and serve immediately.

* Plantin whole black winter truffles available online. 7 to 8 ounces: $70. Rare Tea Cellar, rareteacellar.com