1. For Parmesan pastry, pulse flour, the 2/3 cup Parmesan, and the salt in food processor to blend. Add butter; pulse until mixture resembles course crumbs. Sprinkle 5 tablespoons water over mixture. Pulse, adding remaining 1 to 2 tablespoons water if necessary, just until mixture is moistened and begins to hold together (dough should still be crumbly). Gather dough into a disk; cut in half and shape into two disks. Wrap disks and refrigerate 30 minutes.
2. Meanwhile, heat a 12-inch nonstick skillet over medium-high heat. Add sausage; cook 3 to 5 minutes, until browned. Transfer to bowl with a slotted spoon. Discard excess drippings. Increase heat to high; add chicken to skillet and cook 3 to 5 minutes, turning chicken occasionally, until lightly browned. Add onion; cook 3 to 4 minutes, until tender. Add tomatoes and juice; bring to a boil, breaking up tomatoes with a spoon, then reduce heat and simmer 7 to 8 minutes more. Add sausage and cool.
3. Meanwhile, heat oven to 375 degrees F. Trim stems from chard and coarsely slice leaves and stems. Bring 1/2 cup water, chard stems and leaves to a boil in large pot. Cover and cook 9 to 10 minutes, until stems are tender. Drain in colander, pressing out excess liquid with a spoon.
4. Stir chard into cooled chicken-sausage mixture; divide mixture between two 2-quart baking dishes. Divide and sprinkle 2 tablespoons Parmesan over tops of filling.
5. Roll each pastry disk so it extends 1 inch beyond edge of each baking dish. Place pastry on top of each dish, pressing pastry against side of dish to seal in filling. Cut 2 slits in center of each. Bake pot pies 40 to 45 minutes, until tops are golden and filling is bubbly. Makes 6 servings per pot pie.