1. Heat oven to 450ºF.
2. In food processor, process dried plums, water, vinegar, oil, garlic, rosemary and salt until finely chopped, pulsing on and off.
3. Place bread shell on baking sheet; spread evenly with dried plum mixture. Arrange chicken, cheese and onion slices evenly over shell.
4. Bake in center of oven 8 to 10 min. or until heated through.
5. Cut into 8 wedges.