Put the tomatoes in a food processor or blender and process until smooth. Heat a large skillet or Dutch oven and add the olive oil. Add the onions to the oil and cook, stirring, until soft. Add the tomatoes and pepper. Simmer for 10 minutes uncovered. Add the mostaccioli to the sauce and stir until heated thoroughly. Toss in the fresh basil, parsley, and Parmesan cheese.
Makes 6 servings