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.
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.