Preheat oven to 400ºF (200ºC). Arrange prosciutto slices on parchment paper-lined baking sheet in single layer. Bake 5 min., or until crisp.
Meanwhile, cut bread in half horizontally. Hollow out top and bottom halves by pulling out bread from centres, leaving 1-in. (2.5-cm) thick "shells" (reserve pulled-out bread pieces for another use). Set aside.
Whisk oil with Italian herb seasoning; brush over insides of bread. In bottom half, layer half the arugula, bocconcini, tomato, and prosciutto. Repeat layers once more. Replace top half of bread.
Press down lightly on sandwich to compress layers. Wrap sandwich tightly with plastic wrap. Refrigerate 1 hr. before unwrapping. Cut into 6 wedges. Serve with a green salad or coleslaw.
Add fresh basil leaves, black olives, hot peppers or grated Parmesan cheese to layers.
Pulse excess bread in food processor into crumbs. Freeze and use within 1 month.