4 small russet potatoes (22 to 25 ounces total), peeled, cut into 1/2-inch pieces 1 large egg 2 tablespoons whipping cream 1 1/4 teaspoons salt 1/8 teaspoon ground nutmeg 1 1/2 cups (about) all purpose flour
1 Cook potatoes until tender, about 12 minutes. Working in batches, press warm potatoes through ricer into a large bowl (or place warm potatoes in large bowl and mash finely with potato masher). Cool until lukewarm, about 10 minutes.
2 Add egg, cream, salt, and nutmeg and blend well. Add 1 1/2 cups flour and mix until soft and slightly sticky dough forms, adding more flour by tablespoonfuls if too moist.
3 Turn dough out onto lightly floured work surface. Divide into 6 equal portions. Gently roll 1 dough portion between hands and work surface to 3/4-inch-thick rope about 20 inches long. Cut into 3/4-inch-long pieces.
4 Roll each piece over wires of slender whisk or dinner fork to make grooves in gnocchi. Arrange gnocchi in single layer on floured baking sheet. Repeat with remaining 5 dough portions.
5 Cook 1/3 of gnocchi in large pot of boiling generously salted water until gnocchi rise to top and are cooked through and tender, about 5 minutes (check at 4 minutes). Using large strainer or slotted spoon, transfer gnocchi to serving dish. Cook remaining gnocchi in 2 batches.
(Gnocchi can be prepared ahead. In this case transfer gnocchi to a large baking pan; arrange gnocchi in single layer. Let stand 1 hour at room temperature, or cover and refrigerate up to 2 days.)