How to Make It
Preheat oven to 375°F. Line 2 baking sheets with parchment paper. On a lightly floured surface, roll out 2 pie crusts to a 12-inch circle. Using a pizza cutter or knife, cut about 1-inch off of each side of circle to create approximately an 11x11-inch square. Cut the square horizontally into 3 even strips (approximately 35/8-inches each); then cut the strips in half vertically, creating 6 approximate (35/8 x 51/2-inch) rectangles.
Whisk together 1 cup fruit jam and cornstarch in a medium bowl until smooth. Spoon about 11/2 tablespoons fruit mixture onto 3 of the pastry rectangles. Use a fork to poke holes in non-fruit rectangles. Brush beaten egg around edges of 3 fruit-topped rectangles, then lay remaining 3 rectangles over fruit filling. Use a fork to seal edges of pastry together. Transfer pop-tarts to 1 prepared baking sheet and chill while you repeat process with remaining pie crusts.
Once all pop-tarts have been assembled, bake in preheated oven 18 minutes or until golden. Let cool on baking sheets 5 minutes, then transfer to a wire rack to cool completely, about 30 minutes.
Whisk together remaining 2 tablespoons fruit jam, powdered sugar, and 1 tablespoon cream until smooth. Add up to 1 tablespoon more cream, 1 teaspoon at a time, to reach desired glaze consistency. Spoon glaze over cooled pop-tarts, and top with desired sprinkles. Let glaze dry before serving, about 1 hour or up to 1 day.