Preheat the oven to 425 degrees. Bake the potatoes until a knife pierces them easily, about 1 hour (alternatively, boil them). When the potatoes are almost done, bring a large pot of salted water to a boil over high heat for cooking the gnocchi. Peel the potatoes while they are hot. Cut them into manageable chunks and pass them through a ricer directly onto a work surface. With a table fork, spread the potatoes out until they are about ½ inch thick and let them cool to room temperature.
Drizzle the beaten egg over the potatoes. Sprinkle with nutmeg and salt, then scatter 1 cup flour over the potatoes. Working quickly and gently, use a bench scraper to reach underneath the ingredients and lightly toss them together, as if you were working a pie dough. Continue fluffing the ingredients without kneading them, using the scraper and your free hand, until the mixture resembles very coarse crumbs.
Begin kneading very lightly, much less vigorously than for bread dough. If the dough feels sticky, sprinkle on a little more flour, but as little as necessary to form a dough that is moist but firm and not sticky. The dough should come together in less than 1 minute. When the dough feels like a soft pillow, shape it into a thick log about 8 inches long. With the scraper, cut the log into 6 thick rounds.
Working with 1 round at a time, position it so that a floured side (not a cut side) is up. Lightly flatten it with your palm, then use both palms to roll and stretch the dough into a long, ¾-inch-diameter rope, as if making breadsticks. Flour your work surface or your palms lightly as needed to prevent sticking.
When you have made all 6 ropes, line them up 3 at a time and use the scraper to cut them crosswise into ¾-inch-square nuggets. Flour the nuggets lightly and gently toss them with the flour to prevent sticking.
Now you are ready to shape the gnocchi. Hold a table fork, tines up, in one hand. With the other hand, pick up a gnocco with your thumb and index finger, grasping it on the cut sides. Place it on the tines of the fork as far from the end as possible. With your thumb, gently press the gnocco with a forward movement so that it curls slightly. One side will have the indentations from the tines; the other side will be slightly concave. Keep the gnocchi on the work surface, lightly floured, until you make them all.
Drizzle about 2 tablespoons olive oil into a large baking dish. Boil the gnocchi about 2 dozen at a time. After they float to the surface, count 20 seconds, then lift them out with a skimmer/strainer and transfer them to the oiled baking dish, turning to coat them with the oil. Continue until all the gnocchi are cooked and lightly oiled, adding more oil if needed, then transfer them to a skillet containing your sauce. Reheat them gently in the sauce and serve immediately with a spoon, not tongs.
Yields enough gnocchi for 6 servings PER SERVING: 155 calories, 4 g protein, 31 g carbohydrate, 1 g fat (0 saturated), 35 mg cholesterol, 302 mg sodium, 2 g fiber. .
Almost everyone agrees on one thing: Flour makes gnocchi heavy. The less flour you can incorporate to achieve a workable dough, the better. But that's the catch because the dough is sticky, and it takes a particularly light and practiced touch to shape it with minimal flour.
The potatoes: Most people use fluffy, dry, high-starch potatoes like russets, not waxy new potatoes. Mazzon likes the yellow-fleshed Yukon Golds, which are not as starchy as russets but have better color and flavor. There are no russets in Italy, says Field, and most cooks use a yellow-fleshed potato, the older the better.
The flour: Unbleached all-purpose flour, and as little as possible.
The eggs: Eggs also toughen gnocchi and some deft cooks leave them out, but shaping a dough from only potato and flour, with no egg to bind it, is difficult. Mazzon always uses egg, as did his mother.
Cooking the potatoes: Most recipes call for boiling the potatoes in their skins. A few recipes, including Mazzon's in his book, specify baking the potatoes to minimize the moisture they absorb, and thus the amount of flour needed in the dough. In this demonstration, he boiled the potatoes, and says he does it both ways.
Ricing the potatoes: The cooked potatoes should be peeled immediately and passed through a ricer while hot. A food mill doesn't produce as light a texture, and a food processor makes glue.
Making the dough: The riced potatoes should be allowed to cool before you add the egg and flour. Then the dough should be mixed lightly and quickly by hand, with more flour added only as needed to prevent sticking. As you shape the ropes and cut the gnocchi (see photos), keep the work surface and the dough lightly dusted with flour.
Shaping gnocchi: Cooks use a variety of implements to shape gnocchi, depending on preference and regional style. Shaping them helps them cook more evenly and gives them rough exterior markings that help trap the sauce. The basic idea is to gently press a small nugget of dough against a textured surface with your thumb; by pressing with a slight forward motion, you can make the gnocchi curl like a C.
The simplest implement for shaping is a table fork. Mazzon and many others employ the same technique using the inner side of a convex hand-held cheese grater. Field says she has seen cooks use a sieve. The implement I find easiest to use is a ridged wooden gnocchi (or cavatelli) paddle.
Boiling gnocchi: Bring a large pot of salted water to a boil before you begin making the dough. Gnocchi should be cooked as soon as they are shaped or they will start to stick. Boil only about two dozen at a time. Cook until they rise to the surface, then count about 20 seconds before lifting them out with a slotted strainer. "We say gnocchi is smart pasta," says Mazzon. "They tell you when they are ready."
Saucing gnocchi: Have your sauce ready before you start preparing gnocchi so you can lift them out of the boiling water and transfer them directly to the sauce. Mazzon uses another technique, which works well in a restaurant setting. He lifts them out of the water and into an oiled baking dish, turning them gently to coat them with the oil so they don't stick together. When all the gnocchi are boiled and oiled, he transfers them to the sauce. This is a good technique to use when you are preparing a lot of gnocchi.
Because gnocchi are light, or are meant to be, they should be lightly sauced. Often they are dressed with only melted butter and Parmesan. With gnocchi made of winter squash or spinach, sage leaves are often added to the butter. Among the traditional partners for potato gnocchi are tomato sauce, meat ragu, pesto or mushroom sauce.
Serving gnocchi: In Italy, gnocchi are typically a first course, not a main course. They are filling and should be served in small portions. Be gentle with them. They should not be tossed or handled with tongs or they may break.