Thaw out one sheet of frozen puff pastry dough and roll out into two circles. If you prefer a lace top pie cut one circle in about 12 3/4 inch strips.
Place one circle of the puff pastry on the bottom of the pie dish
Drain the cherries and place the liquid in a small saucepan.
Over a low heat whisk in the cornstarch and lemon juice and mix well
Add the cherries and pour the cherry mixture in the prepared pie dish.
Cover the top of the pie with the 3/4 inch strips and interlace on the top of the pie filling. Seal edges by pinching along the edges. Brush egg whites on top crust.
Cover crust edge with strips of foil to prevent over-browning. Puff pastry is stickier so make sure it loose otherwise it will stick to the edges.
Remove foil strips after about 15 minutes of baking.
Bake an additional 20 to 25 minutes or until the crust is golden brown.