Step 1Mound the flour in the center of a large wooden board. Make a well in the center of the flour and add the eggs. Using a fork, beat the eggs and then incorporate the flour, starting with the inner rim of the well. As you expand the well, keep pushing the flour up to retain the well shape (do not worry if it looks messy). When half of the flour is incorporated, the dough will begin to come together.
Step 2Start kneading the dough, using primarily the palms of your hands. Once the dough is a cohesive mass, set the dough aside and scrape up and discard any dried bits of dough.
Step 3Lightly flour the board and continue kneading for 10 minutes, dusting the board with additional flour as necessary. The dough should be elastic and may be a little sticky. Wrap the dough in plastic wrap and allow to rest for 30 minutes at room temperature before using.
Step 1Divide the pasta dough into 4 pieces. Roll each out on a pasta machine through to the thinnest setting possible without tearing the pasta. Lay the sheets on a floured surface; cover with plastic wrap.
Step 2In a large bowl, combine the ricotta, 1 cup Parmigiano-Reggiano, the eggs, nutmeg and parsley, and mix until thoroughly blended. Season with one-fourth teaspoon salt and the pepper. Set aside.
Step 3To make the tortelloni, cut the pasta sheets into 3-inch squares, cutting only 4 or so at a time so that the pasta doesn't dry out while you are assembling the tortelloni. Place a generous teaspoon of the filling in the center of each square, fold the dough over to form a triangle, and press the edges together to seal. Then bring the two bottom points together, overlapping them slightly, and pinch together to seal. Transfer the tortelloni to a baking sheet lined with a kitchen towel.
Step 4Bring 6 quarts of water to a boil in a large pot, and add the remaining 2 tablespoons of salt. Meanwhile, in a 12-inch saute pan, melt the butter with the sage leaves. Set aside.
Step 5Drop the pasta into the boiling water. Cook at a brisk simmer until tender, 3 to 4 minutes.
Step 6Turn off the heat and, using a slotted spoon or spider, remove the tortelloni from the water, draining well, and place in the pan with the butter and sage. Toss to coat, then add the remaining one-half cup of Parmigiano and toss gently over medium heat until the pasta is well coated and cheese has slightly melted. Transfer to a warmed serving bowl and serve immediately.