Homemade Raspberry Pop Tarts

To make the pastry: In your food processor, add flour, salt, and baking powder and pulse briefly until combined. Add butter pieces and pulse until crumbly. Add sour cream and pulse briefly until dough comes together.
Turn your dough out onto a floured work surface, and bring it together with a few quick kneads.
Pat the dough into a rough log, and roll it into an 8" x 10" rectangle. Dust both sides of the dough with flour, and starting with a shorter end, fold it in three like a business letter.
Flip the dough over, give it a 90u0b0 turn on your work surface, and roll it again into an 8" x 10" rectangle. Fold it in three again.
Wrap the dough, and chill for at least 30 minutes before using.
Preheat your oven to 425u0b0F and place a rack on the middle shelf. Line a baking sheet with parchment paper.
Roll out the dough into a 12" x 16" rectangle. Using a knife, cut out twelve 4" squares (or whatever dimensions you like - just make sure you have a top and a bottom for each pop tart!)
Spoon 2 tablespoons raspberry jam onto 6 of the pastry squares.
Cut a vent (or poke with a fork) into each of the remaining 6 squares, then top each pop tart with a vented square, and press along the edges with the tines of a fork to seal.
In a small bowl, whisk the egg, and brush the egg mixture over the tops of each pie. Transfer the pies to the prepared baking sheet.
Bake for 15 to 20 minutes in your 425u0b0F oven. Let cool.