In a large bowl, combine the sugar, flour and cinnamon; add apples and toss to coat. On a lightly floured surface, roll out each pastry sheet into a 12-in. square. Cut each into four squares. , Spoon 1/2 cup apple mixture into the center of each square; fold diagonally in half and press edges to seal. Place on a parchment-lined baking sheet., In a small bowl, combine the butter, sugar and cinnamon; brush over pastry. Bake at 400° for 12-16 minutes or until golden brown. Serve warm with ice cream if desired.