Prep: 4 minutes; Cook: 10 minutes
1. Preheat oven to 375°.
2. Place flatbread on rack in oven; bake at 375° for 3 minutes or until lightly browned. Remove flatbread from oven; top with grapes, cheese, and walnuts. Place flatbread back on rack in oven; bake 5 minutes or until cheese melts and crust is browned.
3. While pizza bakes, bring vinegar to a boil in a small saucepan. Boil 1 minute or until vinegar thickens and reduces to about 1/2 tablespoon. Top pizza with arugula; drizzle with balsamic syrup. Serve immediately.