Heat oven to 450º. Line jelly roll pan, 15 1/2x10 1/2x1 inch, with aluminum foil. Spread tomatoes, bell pepper and onion on foil. Brush both sides of vegetables with about half of the dressing. Bake uncovered 12 to 15 minutes or until onion is crisp-tender.
Reduce oven temperature to 375º. Remove vegetables and foil from pan. Place bread halves, cut sides up, in pan. Brush with remaining dressing. Top evenly with roasted vegetables, eggs, olives and cheese.
Bake 8 to 10 minutes or until cheese is melted. Cut into 2-inch slices.