Homemade Blueberry Pop Tarts

Filling:
Place blueberries in a medium bowl and crush them.
In a small saucepan, combine blueberries, sugar, and lemon juice.
Cook over medium low heat until sugar dissolves and mixture thickens.
Remove from heat. Cool.
Place blueberry mixture in a food processor and pulse until mostly smooth. Set aside.

Pastry:
In the bowl of a food processor, combine flour, salt, baking powder, and sugar.
Pulse a few times to combine.
Add butter, a few pieces at a time, pulsing after each addition.
Add egg and pulse a few times to combine.
Add cream and pulse until mixture comes together.
Turn out onto a piece of plastic wrap.
Lightly form into a ball and press out into a disc.
Wrap tightly.
Place in refrigerator for 30 minutes.
Turn out dough onto lightly floured parchment paper.
Roll out into a rectangle, 1/4" thick.
Trim edges of pastry.
Using a rectangular cutter, cut out as many rectangles as possible.
Remove dough rectangles to a cookie sheet lined with parchment.
Gather scraps and re-roll.
Cut out rectangles. You should have 18 total between the 2 rolls.

Egg Wash:
In a small bowl, whisk together the egg yolk and the cream.

Putting It Together:
Preheat oven to 350 degrees.
Line baking sheet with parchment paper.
Place 9 squares of dough on parchment-lined baking sheet.
Brush the edges of each square with egg wash.
Spoon a heaping Tablespoon of blueberry jam in the center of each rectangle.
Spread the jam out to about 1/2" from the edge.
Top with another rectangle.
Gently press down edges to seal.
Use a fork on all four sides of each pop tart to make sure they are sealed.
Using a fork, poke holes in the top of the pastry.
Bake until light brown, about 25 minutes.

Frosting
Combine powdered sugar, milk, and vanilla in a small bowl.
Beat until smooth.