PREHEAT oven to 375°F. Combine pineapple, sugar, syrup and mustard in medium saucepan. Cook on medium-high heat until sugar is completely dissolved, stirring occasionally. Add ham and onions; stir until well blended.

UNROLL bread dough onto baking sheet sprayed with cooking spray. Press into 14x12-inch rectangle. Spread ham mixture onto half of the dough; fold dough in half to enclose filling. Press edges firmly together to seal. Cut several slits in top of dough to allow steam to escape.

BAKE 18 to 21 min. or until golden brown. Let stand 5 min. before cutting to serve.