Penne with pumpkin sauce

1 onion, chopped fine
 1 red bell pepper, chopped fine
 2 large garlic cloves, minced
 2 tablespoons unsalted butter
 1/2 cup canned solid-pack pumpkin
 1 cup chicken broth
 1/2 cup water
 2 tablespoons heavy cream 
 Freshly grated nutmeg to taste 
 1/2 pound penne or other tubular pasta
 3 tablespoons minced fresh parsley leaves
 Freshly grated Parmesan as an accompaniment
 In a large skillet cook the onion, the bell pepper, and the garlic in the
 butter over moderate heat, stirring, until the vegetables are softened. Stir
 in the pumpkin, the broth, the water, the cream, the nutmeg, and salt and
 pepper to taste, and simmer the sauce, stirring occasionally, for 10 minutes.
 
 While the sauce is simmering, in a kettle of salted boiling water boil the
 penne until it is al dente. Reserve about 1 cup of the cooking water, and
 drain the penne well.
 
 Add the penne to the sauce, cook the mixture over moderate heat, stirring
 and thinning the sauce as desired with some of the reserved cooking water,
 for 1 to 2 minutes, or until the pasta is coated well, and stir in the
 parsley. Divide the pasta between 2 plates and serve it with the Parmesan.