In a small mixing bowl combine all the filling ingredients, stir until smooth
Roll the chilled pie crust out on a lightly floured counter top until about 1/4 inch thick
Cut out small rectangles with a cookie cutter or leave it as a big, sheet pan sized, rectangle.
Spoon about 1 tablespoon of filling in half of the small rectangles, or pour all the filling in if you opted for the sheet pan size.
Place an unfilled dough rectangle on top of a filled rectangle, making a sandwich.
Using a fork, press & crimp the edges of each pop tart, then poke the top of each pie to make sure they have proper ventilation.
Transfer the pop tarts to a light metal cookie sheet lined with parchment paper. Whisk the egg in a bowl and using a pastry brush, egg wash the tops of each pie.
Place in the oven and bake for 13-15 minutes until lightly golden.
While the pop tarts are baking, in a small mixing bowl, whisk all of the frosting ingredients together.
Remove from the oven and spoon on the frosting while the pop tarts are still a bit warm.
Allow the frosting to set for 20-30 minutes before enjoying!