On a lightly floured surface, roll out the dough to 1/8 inch thick. Use a straight edge ruler and a pastry wheel to cut 3x3 inch squares. Gather up the scraps, roll them out again, and cut as many squares as you can. You should be able to cut about 32 squares, for 16 pop tarts.If you like, cut them bigger, like a 3x5 rectangle, for a traditional pop tart shape. You can also try hearts, circles, or any shape you like.
Filling
If making homemade Bourbon Cherry Jam, you should make it the day before, or several days in advance, so it's ready to go when you roll out the dough.
You can use absolutely any flavor of jam that you like, or even prepared pie filling.
Assembly
Place half of the squares on a large baking sheet lined with a sheet of parchment paper or nonstick baking paper, spacing them 1 1/2 inches apart.
Spoon about 2 teaspoons of jam onto each square.
Lightly beat the egg, then use a pastry brush to lightly brush the edges of each square of dough with the egg wash. Place the other half of the dough squares on top, and gently press down the edges to seal the two squares together. Brush the top of the pop tarts with the egg wash.
Use a fork to press decorative indentations around the edges, then use a small, sharp knife to poke a few slits in the top of the dough, to let the steam vent.
Place the pan in the refrigerator to chill for 20 minutes, or if you have space in the freezer, freeze for 10 minutes.
Bake
Preheat the oven to 375 F, and position a rack in the center of the oven.
Bake the chilled pop tarts for about 25-30 minutes, until flaky and golden brown.
Transfer the pop tarts to a cooling rack, place the cooling rack over the baking sheet, and let them cool for several minutes while you make the icing.
Icing
In a bowl, whisk together all of the icing ingredients until smooth and thick. Spoon the icing on top of the warm pop tarts, and spread it towards the edges.
Before the icing sets and crusts over, sprinkle on some coarse Turbinado sugar or sprinkles.
The icing will set in about 15-20 minutes.
Notes
Make Ahead: You can completely assemble the pop tarts at night, and keep them refrigerated (unbaked) in an airtight container. In the morning, just pop them in the oven!
Storing Leftovers: Cool the pop tarts completely, then store at room temperature in an airtight container for up to 2 days.