Place the flour and sugar into a food processor. Pulse a few times to combine.
Add the cold cubed butter and pulse until combined, the butter should be broken up and there should be no butter pieces larger than a pea.
Add the vanilla. Slowly stream in the water while the food processor is running. You want the crust just to come together, do not overmix.
Form the crust into a ball and cover it with plastic wrap. Place in the fridge for 20-30 minutes to chill.
Preheat the oven to 400°F. Line a large sheet tray with parchment paper, and set it aside.
Make the filling by stirring together the brown sugar, butter, flour, and cinnamon until fully combined. Set aside.
On a lightly floured, clean work surface, roll out the dough into a 1/4th inch thick rough rectangle shape.
Cut out rectangles from the dough using a 3×4 inch rectangle cookie cutter or something of similar size. You will need to roll out the scraps of dough again to cut more rectangles. We need 12 pieces.
Place 6 of the crusts onto the prepared sheet tray, not touching.
Place just under 2 tablespoons of the filling into the center of each crust with a ¼ inch border along the edges.
Top with another crust and gently press down the edges. Take a fork and press the edges together to seal. Take the same fork and make 6 rows of ventilation holes over the center of the tarts.
Bake for 15-18 minutes until golden brown. Let cool completely.
Whisk together the powdered sugar, cinnamon, milk, and vanilla extract for the glaze. We want the glaze to be very thick but still pourable. Start with 1 tablespoon of the milk and add a little more at a time until the desired consistency.
Place the tarts onto a wire rack over a sheet tray to catch any drips. Spoon the glaze on top of the tarts. Let the glaze set for 20 minutes.
Notes
This makes 6 large pop-tarts, but you can easily double it to feed more.
Other spices can be used, see above for how to do that.
We love to enjoy these warm, pop them in the microwave for a few seconds. Do not toast them as they are glazed.
Easily make the dough ahead of time for a quick treat.
Use store-bought pie crusts in the box instead of making the dough.
These can be frozen, see above on how to do that.
Use this as a base recipe to make different flavors.
Use dark brown sugar in place of light if that's what you have on hand.