PREHEAT oven to 400°F. Cut pastry in half along perforated line; roll out one piece to 12-inch square. Spread with 2 Tbsp. of the mustard; top with half each of the cheese and meat.
ROLL up pastry from opposite sides to make two rolls that meet in the centre. Repeat with remaining pastry and filling; cover. Refrigerate 20 min. Cut each roll into 20 slices, each about 1/4 inch thick. Place, cut-sides up, on lightly greased baking sheets.
BAKE 15 min. or until browned.