Prepare as above except omit filling mushroom caps with shredded cheese. Transfer grilled vegetables to a cutting board. Cut vegetables into bite-size pieces. Split one 8-inch loaf Italian flat bread (focaccia) in half horizontally. Place halves, cut sides down, on grill rack over medium heat. Grill for 1 to 2 minutes or until lightly browned. Remove bread from grill. Turn bottom half of bread, cut side up. Sprinkle with 3/4 cup of the cheese. Grill 1 to 2 minutes more or until cheese is melted. Place bottom half, cheese side up, on a serving platter. Top with chopped vegetables. Sprinkle with remaining shredded cheese. Add top of bread, cut side down. Cut into 4 wedges to serve.