Step 1

Blend berries in a high speed blender and strain into a small pot to remove seeds

Step 2

Add sugar, vanilla, and 1 tbsp flour and whisk together with the berries

Step 3

Heat at medium heat and bring to a boil

Step 4

Once the filling is boiling lower the heat and whisk constantly until a spatula can scrape against the bottom of the pot and the filling slowly seeps back to the center

Step 5

Remove from heat and pour into a small bowl, set aside

Step 6

Add flour and cold butter to a food processor and pulse until crumbly

Step 7

Add salt and water 1 tbsp at a time until it forms a ball

Step 8

Remove dough and place onto a lightly floured surface and press together into a rectangle

Step 9

Wrap with plastic wrap and place in the fridge for 30 minutes

Step 10

Preheat oven to 400 degrees

Step 11

Place chilled dough on a floured surface and roll out to 1/8 inch thick

Step 12

Cut into even rectangles with a pizza cutter and place half of them as the bottoms on a parchment lined baking sheet

Step 13

Fill each rectangle with 3 tsp blackberry filling and place the top of each pastry on top

Step 14

Using a fork press the top and bottom edges together so the filling stays in as it cooks

Step 15

Bake for 18 minutes

Step 16

Cool completely before frosting

Step 17

Smash 1/3 cup fresh blackberries until they are pureed, strain the seeds out and place into a small bowl

Step 18

Whisk powdered sugar into blackberry puree until completely combined

Step 19

Frost each blackberry pop tart with frosting and top with blue star sprinkles