In a large pot, combine broth, water and salt. Bring to a boil, add chicken, then boil uncovered for about 20 minutes.
Meanwhile, in a large pan, heat oil over medium. Add onions and sauté until softened, about 5 minutes; increase heat to medium-high, add grated carrots and celery and sauté 5 to 7 minutes, stirring, until soft and golden; transfer to pot.
Remove chicken, cool, and shred. Return to pot, add pasta, sliced carrots and corn; continue cooking for 15 minutes at a low boil until pasta is cooked.
In a medium sauce pan over medium heat, melt butter, whisk in flour and cook, whisking constantly for 1 to 2 minutes or until golden. Add 1 cup broth from pot into flour mixture, whisking until well blended, then whisk in heavy cream; transfer mixture to pot and stir. Season with salt to taste, if needed. Add dill, return to a boil, and turn off heat. Serves 8.
Approximate Nutrient Analysis per serving:
330 calories, 19 g fat, 8 g saturated fat, 120 mg cholesterol, 600 mg sodium, 24 g carbohydrate, 2 g fiber, 4 g sugar, 19 g protein