ingredients:

Pastry

1/4 cup minus 2 teaspoons of very cold water

Filling

1/2 can Cherry Pie filling (You can use the light version with less sugar - or
homemade is even better) *can sub for any kind of jam as well

Optional

1/4 cup milk 

Glaze

1-2 cups powdered sugar (depends on desired glaze consistency)

Preheat oven to 400 degrees F.  Line two baking sheets with parchment paper and set aside.

1. In a medium bowl, stir together flour, baking powder, salt, and brown sugar.  Add cold butter, and cut into small pieces using a pastry cutter, or simply a fork.  You want the pieces of butter to be about the size of a pea, but no smaller. 
2. Note:  Another method of cutting in the butter is to use frozen butter, and simply grate it with a cheese grater.  Both methods work well.
3. In a liquid measuring cup, add 2 teaspoons of vinegar, and then top with very cold water until it reaches the 1/4 cup mark.  Poor water over flour mixture, and stir together.  Lightly flour your working surface, and dump pastry dough out onto it.  Carefully work with hands until the dough has just come together, we don't want to overmix it here.
4. Wrap dough in plastic wrap, and place in the fridge for at least half an hour.  
5. Remove dough from fridge, and roll out onto a lightly floured surface.  Roll out the dough to about 1/8 of an inch thick.  You want to get about 12 rectangles that are about 3"x2" in size.  Use a rectangular cookie cutter, or simply a pizza cutter to cut out rectangles.  Place 2 or 3 tablespoons of cherry filling onto half of the rectangles.  Dip your finger in a bit of water and run it along the outside border of the rectangle that has the filling in it, and then place a second rectangle of dough over top and press the edges together.  The water will help the dough bind together.  Use a fork to press edges together further.  Repeat for all rectangles.  Use fork to poke a few holes in the top of each pop tart.  Place the pop tarts on the parchment lined pans, and return to the fridge for 15 minutes.  Don't skip this step!  We want the butter in the dough to be nice and cold before it goes into the oven so that our crust is nice and flaky.
6. Remove pans from fridge and use a pastry brush to brush on either an egg wash, or a bit of milk to promote nice browning of the pastry.  Sprinkle with coarse sanding sugar if desired.  Bake for 20 minutes, or until dough is golden, and filling may begin to bubble.  Remove and allow to cool slightly.
7. Meanwhile, make the glaze by mixing the cherry pie filling, vanilla, soft butter, and 1 cup of powdered sugar together until smooth.  If you use any of the actual cherries in the glaze, use a small blender to blend ingredients together until smooth.  Add more powdered sugar until desired consistency is reached.  Pour glaze over pop tarts and top with sprinkles, and serve.