Defrost the pastry sheet - it takes about 20 minutes.
On a floured surface roll out the pastry sheet in one direction so that it makes a longer rectangle. The final rectangle will measure 12" x 18".
In a bowl mix the cornstarch, melted jelly and cinnamon together.
Add the apples and cranberries - mix well.
Cut the sheet down the center, lengthwise, so that there are 6" on each side.
Now cut each side, twice, so that there are 6 squares that measure 6" x 6".
Dollop the apple mixture, evenly in the center of each square.
Dot the vegan butter on top of each pile of the apple mixture.
Fold over the squares to line up the edges to form a triangle.
Press the edges with your fingertips and fold over a small edge if you can.
Use the tines of a fork to go around the edges to crimp a better seal.
Place on a lightly oiled baking sheet.
Bake ay 400 degrees for 20 minutes.
Remove from the oven and then place the turnovers on a rack to cool.
Sprinkle powdered sugar over the top of the turnovers, if you wish.