1. Preheat oven to 350°.
2. Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add eggplant, bell pepper, and onion; sauté 5 minutes or until tender. Stir in 1/4 teaspoon salt; sauté 5 minutes. Set aside.
3. Weigh or lightly spoon flour into a dry measuring cup; level with a knife. Place flour in a medium saucepan; add milk, stirring with a whisk. Bring to a boil over medium heat, and cook milk mixture for 1 minute or until thick, stirring constantly. Add 3 tablespoons cheese, stirring until cheese melts. Remove from heat; stir in remaining 1/4 teaspoon salt and ground red pepper. Let stand for 15 minutes.
4. Combine eggs and egg whites in a medium bowl, stirring with a whisk. Stir in oregano. Gradually add hot milk mixture to egg mixture, stirring constantly with a whisk. Fold in eggplant mixture; pour into an 11 x 7-inch glass or ceramic baking dish coated with cooking spray. Sprinkle with the remaining 2 tablespoons cheese. Bake at 350° for 30 minutes or until puffy and set. Garnish with parsley, if desired. Serve immediately.