In a mixer fitted with a paddle attachment, add the sifted dry ingredients. Add the butter and mix until it combines with the dry ingredients. Add the corn syrup and mix until a ball is formed. Let the dough rest for 2 hours in a cool place.
Make the filling while the dough rests. In a saucepot, bring the fruit to a boil. Combine the dry ingredients. Once the fruit has released its juices and has come to a boil, add the dry ingredients. While whisking, bring the mixture to a boil and hold at a boil for 3 minutes. Let cool.
Roll the dough onto a floured surface until it is 3 mm thick. Cut the rolled dough in half. Cut one half of the dough into the 3 x 5 inch rectangles. Cut the second half of the dough into 3¼ inch x 5¼ inch rectangles - these slightly larger rectangles will be the top of the pop tarts. Pre-heat oven to 350 degrees.
Place the bottom pop tart dough rectangles on a parchment or Silpat lined baking sheet. With a pastry brush, paint the egg wash around the outside edge of the dough. Put the cooled pop tart filling inside of the egg wash rectangle. Add the larger rectangle dough on top of the filling. On one side of the rectangle, press the two pieces of the dough together, fastening them with a fork. Brush the top of the pop tart with egg wash.
Combine the egg and water with a fork or a whisk.
Bake until a light golden brown 15-20 minutes. Let cool. Using a spoon, knife, brush, palette knife or hands, spread or dip the cooled pop tart. Let dry and enjoy.