In a medium-sized saucepan, combine strawberries, sugar, cornstarch, and lemon juice over medium-low heat.
Stir frequently until strawberries release their juices.
Use a potato masher to crush the strawberries until mostly liquid (it's fine if small pieces are remaining).
Increase heat to medium-high and bring to a boil, stirring constantly.
Boil (still stirring constantly) for 3 minutes and remove from heat.
Stir in vanilla extract. Continue to occasionally stir the mixture so that it doesn't burn to the bottom of the pan.
Pour into a canning jar and place in the refrigerator until you are ready to use.
In a food processor, pulse together flour, sugar, and salt.
Sprinkle in chopped, cold butter and pulse until coarse crumbs begin to form.
Add the sour cream and pulse until the dough begins to clump together.
Deposit the dough out onto clean, well-floured surface and lightly dust with more flour.
Knead dough, adding flour as needed, until it is cohesive and no longer sticky
Using your palm, flatten the dough on the clean surface.
Fold the dough into itself twice and repeat the flattening process (this helps encourage flaky layers in the crust).
Repeat the folding and flattening process once more.
Divide the pastry dough into two pieces and form each into a smooth ball. Slightly flatten into a disk, wrap tightly with clear wrap and place in fridge to chill for at least 30 minutes.
After the dough has chilled, remove from refrigerator.
Remove clear wrap from dough (working with one disk at a time) and turn dough out onto a clean, lightly floured surface.
Use a rolling pin to roll each disk into a roughly 9x12 rectangle (I always make it larger and then trim the edges, I use a pizza cutter for even cuts).
Cut into 3x4 pieces (I'm a stickler so I use a ruler to make sure they're even, but this isn't necessary and even still my pop tarts end up with slightly varied sizes).
Place two 3x4 piece of crust on a parchment paper lined cookie sheet.
Prepare your egg wash by stirring together your egg and 2 tsp of water with a fork until well-combined.
Brush the surfaces of both pastry pieces with egg wash using a pastry brush (do not discard the egg wash, you will use it again before putting the pop tarts in the oven).
Place 1 heaping Tbsp of filling in the center of one piece of crust, and then place the second piece of pastry on top (the egg-washed side should be facing the filling).
Crimp the edges with a fork to seal, and then use a sharp knife to pierce small holes throughout the pastry.
Repeat until all of your dough has been used.
Chill pop tarts on cookie sheet in refrigerator for 20 minutes.
Once pop tarts have finished chilling, brush with remaining egg wash and transfer to oven.
Bake on 400 for 25 minutes or until edges are beginning to turn golden-brown.
Allow to cool completely before frosting.
Prepare glaze by whisking together powdered sugar, heavy cream, and vanilla extract.
Spread over each pop tart and decorate with sprinkles, if desired.
Allow the pop tarts to sit at least 10-15 minutes for the frosting to set.
*I prefer to prepare my jam filling a day in advance. It gives the filling ample time to cool, and it firms up and is easier to portion once it has been refrigerated. Unlike storebought pop-tarts, once these have been frosted they won't hold up to a toaster (the icing will melt right off). I like to pop mine in the microwave for a few seconds, just be warned that the icing becomes pretty melty when heated.
Homemade Strawberry Pop Tarts https://sugarspunrun.com/homemade-strawberry-pop-tarts/ Find more great recipes at SugarSpunRun.com!