Cook the spaghetti according to the directions, less 2 minutes
Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the onions, green peppers, and garlic. Saute until the vegetables are tender, 6 to 10 minutes
Once the vegetables are tender stir in the tomato sauce and diced tomatoes.
Add the oregano, basil, and the parsley and stir in.
Mix in 16 ounces (2 cups) mozzarella cheese and the Parmesan cheese. Stir until the cheese is mostly melted.
Toss in the cooked spaghetti noodles.
Pour into a 9 by 13-inch baking dish. Top with the remaining mozzarella cheese.
Place in an oven that has been preheated to 350 degrees F. Bake for 30 to 35 minute or until the cheese is melted and slightly browned over top.