Heat oven to 350º Spray a 13 x 9 baking dish with nonstick cooking spray.
Cook pasta shells as directed on the package. Drain; cover to keep warm.
Heat olive oil in a large skillet over medium heat until hot. Add bell pepper, onion and garlic. Cook and stir 2 to 3 minutes or until crisp tender. Add eggplant and zucchini; cook and stir 3 minutes. Stir in tomatoes, oil and 1/4 cup of the tomato sauce. Cook until heated through, stirring frequently, 10 minutes. Cool.
In medium bowl, stir together Romano cheese, ricotta cheese, and Italian seasoning. Add cooled vegetable mixture to ricotta mixture, mix well.
Fill each cooked pasta shell with about 1/4 cup vegetable/cheese mixture. Place in sprayed baking dish. Spoon remaining pasta sauce over shells.
Cover with foil. Bake 30 minutes.
Uncover baking dish; sprinkle with remaining cheese.
Bake uncovered 5 to 10 minutes longer or until bubbly and cheese is melted.