Cut bread in half horizontally, using a serrated knife. Top bottom bread half with prosciutto and next 3 ingredients. Drizzle with balsamic vinaigrette; cover with top bread half. Wrap in aluminum foil; place on a baking sheet.
Bake at 350° for 15 minutes or until warm. Cut focaccia into six wedges. Serve immediately.
*6 ounces of ham may be substituted for prosciutto for approximately the same amount of calories.