Fill a large pot with lightly salted water, and bring to a rolling boil over high heat. Stir in the shell pasta, and return to a boil. Cook, stirring occasionally, until cooked through but still firm to the bite, about 13 minutes. Drain well.
While the pasta is cooking, heat the vegetable oil in a large skillet over medium-high heat. Cook onion, orange pepper, and garlic in oil until tender, about 5 minutes. Stir the crumbled Italian sausage into the vegetables in the skillet; cook and stir until meat is browned and cooked through, about 8 minutes. Stir in the undrained tomatoes and the heavy cream. Turn the heat to medium-low, and allow the sauce to cook until thick, about 5 additional minutes.
Mix pasta with the sausage cream sauce, stir in the Parmesan cheese, and serve. Garnish with chopped fresh parsley.