Heat oven to 375°F.
In a large non-stick skillet, brown sausage, onion, garlic, Italian seasoning, salt, pepper and bell pepper over medium heat. Make sure to break up the sausage and drain any excess oil. Add marinara sauce and diced tomatoes to the meat and let simmer for 5-10 minutes, uncovered. Add cooked spaghetti and parsley and mix together.
Spread mixture into a 9x13 baking pan, top with cheese and bake for 25-30 minutes. Cut into squares and serve. Makes 8 servings.
Approximate Nutrient Analysis per serving (not including salt to taste ingredients):
550 calories, 23 g fat, 9 g saturated fat, 55 mg cholesterol, 1200 mg sodium, 57 g carbohydrate, 4 g fiber, 9 g sugar, 26 g protein