Three Cheese Ravioli

Preparation : Bring the pasta dough to room temperature and roll one piece through the rollers of a pasta machine, set to its highest number. After rolling out, trim the ends so that the dough is an even rectangle. Lower the setting on the pasta machine one notch down. Dust both sides of the dough with flour and feed the dough back carefully through the machine. Continue to cycle the dough through the machine, each time turning the dial one notch lower, so that the sheets become longer and thinner with each pass. Stop when you reach the second lowest number and cut the pasta sheet into 2 pieces, one slightly longer than the other. Place these sheets on a floured sheet tray; cover with plastic wrap and a slightly damp towel. Repeat the process with the remaining pasta dough. To make ravioli, working with one set of pasta sheets at a time, put heaping tablespoons of the filling in lengthwise rows on the shorter sheet of pasta, spacing them about 1 inch from the edges and 3 inches apart from each other. Brush the dough around each mound of filling with beaten egg and then put the longer piece of dough on top. Press the dough gently around the filling and push out any air bubbles. With a circular pastry cutter or knife cut the dough between the rows of filling into individual ravioli. Place the ravioli in one layer on a lightly floured tray as you make them. Once finished, the ravioli can be kept, uncovered in the refrigerator for up to 2 hours. To cook, bring 2 quarts of salted water to a rapid boil and add the ravioli. Cook them at a steady simmer for 6 to 8 minutes, or until they are al dente. Sauce as desired.