How to Make It
In a food processor, pulse the 00 flour with the salt. In a medium bowl, whisk the egg yolks with the whole eggs and 2 tablespoons of water. Add the eggs to the flour and pulse until the dough just comes together. Transfer the dough to a lightly floured work surface and knead until smooth, about 5 minutes. Cover with plastic wrap and let stand at room temperature for 20 to 30 minutes.
Divide the dough into 3 pieces and work with 1 piece at a time, keeping the rest covered. Press the dough to flatten it slightly. Using a pasta machine set at the widest setting, run the dough through successively narrower settings until you reach the thinnest one. Cut the pasta sheet into 10-inch lengths, lay them on a lightly floured work surface and generously dust with semolina. Repeat with the remaining dough.
Fold the pasta sheets in half lengthwise, then, using a very sharp knife, cut them into scant 3/4-inch-wide ribbons. Transfer the pappardelle to a large baking sheet and dust with more semolina. Let the pappardelle stand at room temperature for 30 minutes before cooking in salted boiling water until al dente, 2 to 3 minutes.
Doppio zero (“double zero,” or 00) flour is a fine Italian flour available at specialty food shops and amazon.com.