Preheat oven to 425 or according to pie crust baking instructions. Lay out pie crust on a flat service. Use cookie cutters of your choice to make your favorite shaped pop tarts. Cut out 2 shapes per each pastry and set aside.
In a bowl add a couple drops of water to the cornstarch and mix until it's becomes a thick liquid. Then pour in and mix in the strawberry jam. Make sure it remains thick and not watery.
Lay your single shaped pie crust pastry onto a greased baking sheet. Fill with a couple small spoonfuls of the jam mixture. Spread it evenly in the center of the pastry.
Lay the second pastry on top so all edges line up evenly. Use a fork and press it along the edges to seal the filling inside. You can also poke a couple small holes on the top of the pastry so it doesn't form baking bubbles.
If you want your pastry to have a shinny gloss, mix an egg white in a bowl and brush the top with the egg whites (this is optional).
Place pastries in the oven for about 15 minutes (check pie crust instructions).
While the pastries are baking, it's time to make the icing. In a small-mid sized bowl pour in powdered sugar. Slowly add milk and mix until it becomes thick. You can add your favorite food coloring, but it's totally optional. Side aside until pop tarts are done and cooled.
Drizzle icing on top of cooled pop tarts and decorate with sprinkles or toppings of your choice.