In a mixing bowl, stir together cooked chard, ricotta, Parmigiano, eggs and nutmeg until well blended and season with salt and pepper.
Lay pasta sheets out on to work surface and cut into 2 inch squares. Place 2 teaspoons chard mixture in center of each and fold into rectangles, pressing firmly on all edges to seal.
Bring 6 quarts water to boil and add 2 tablespoons salt. Place tortelli carefully in water, lower heat to high simmer, and cook 3 to 4 minutes until tender. Melt butter in a 12 to 14 inch saute pan. Drain tortelli carefully and place in pan with butter. Toss to coat and serve immediately with grated cheese on the side.
Make a mound of the flour in the center of a large wooden cutting board. Make a well in the middle of the flour and add the eggs, oil and any other flavoring you choose. Using a fork, beat together the eggs, oil and flavorings and begin to 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 that this initial phase looks messy. The dough will come together when 1/2 of the flour is incorporated.
Start kneading the dough with both hands, using the palms of your hands primarily. Once you have a cohesive mass, remove the dough from the board and scrape up any left over crusty bits. Lightly flour the board and continue kneading for 3 more minutes. The dough should be elastic and a little sticky. Continue to knead for another 3 minutes, remembering to dust your board when necessary. Wrap the dough in plastic and allow to rest for 30 minutes at room temperature. Note: do not skip the kneading or resting portion of this recipe, they are essential for a light pasta.
Recipe Courtesy of Mario Batali