The secret to this dish is wonton wrappers, which are used in place of pasta. Available at most Asian-food stores, they come in packages of about 100; wrap unused wrappers in plastic, and freeze. (You may want to freeze them in single-recipe-size batches.)
Source: Martha Stewart Living, August 2002
3/4 pound ruby chard, washed and dried
1 1/2 tablespoons unsalted butter
1 medium shallot, minced
6 fresh sprigs thyme
Salt and freshly ground pepper
6 tablespoons ricotta cheese
3 tablespoons freshly grated Parmesan cheese
1 3/4 cups Homemade Chicken Stock Homemade Chicken Stock (http://www.marthastewart.com/261561/homemade-chicken-stock), or canned low-sodium chicken broth, skimmed of fat
24 three-and-a-half-inch square wonton wrappers
1 large egg, lightly beaten
Separate stems of chard from leaves. Dice stems, and set aside. Coarsely chop leaves; there should be about 3 cups of packed leaves.
Melt butter in a medium skillet over medium heat. Add shallot, and cook, stirring, until translucent, about 30 seconds. Add chard leaves, 3/4 teaspoon thyme leaves, salt, and pepper to taste. Cook, stirring, until leaves are completely wilted, about 2 minutes. Transfer to a medium bowl, and refrigerate until cool, about 5 minutes. Stir in ricotta, Parmesan, and salt and pepper to taste.
Combine stock, 1 sprig thyme, and chard stems in a small saucepan. Bring to a boil. Lower heat to a simmer, and cook for 3 minutes. Remove from heat. Allow to sit until the liquid is dark pink, 5 to 10 minutes. Strain through a sieve, season with salt and pepper, and reserve.
Bring a large pot of water to a boil. Meanwhile, lay 12 wonton wrappers on a clean work surface. Place a slightly heaping tablespoon of filling in center of each wrapper. Brush edges with beaten egg. Top each square with a second wrapper. Press edges together to seal.
Add salt to boiling water. Add ravioli to boiling water, and cook until translucent and floating, 1 to 2 minutes. (Work in batches if necessary.) Remove from water with a slotted spoon. Ladle about 1/4 cup broth into each of four shallow bowls. Place three ravioli in each bowl. Garnish with remaining thyme leaves.