1. Preheat oven to 475°.
2. Coat a medium skillet with cooking spray. Place over medium-high heat until hot. Add mushrooms and cook, stirring constantly, 5 minutes or until golden. Set aside.
3. Place bread shell on an ungreased baking sheet or pizza pan. Top bread shell with mushrooms, tomato, onion, bell pepper, basil, and olives; sprinkle with mozzerella, Parmesan, and Romano cheeses. Bake at 475° for 6 to 9 minutes or until cheeses melt. Cut into 8 wedges.