Roll your pie crust dough into a rectangle. Using a knife or pizza cutter cut that rectangle into smaller ones. Depending on how big you want your poptarts to be they could be 3" by 5" or 5" by 7". Then using the tines of a fork poke holes in them.
Place your filling in the middle of one of the rectangles.
Take another rectangle place it on top and pinch all four sides together. If wanted use the tines of a fork to crimp the edge.
Brush egg on the top of each assembled poptart and bake for 350° for 20 minutes.
Once cooled top with icing and sprinkles if desired.