In a mixing bowl, combine the all-purpose flour, granulated sugar, and salt.

Add the cubed cold butter and mix until the mixture resembles coarse crumbs.

Gradually add ice water, mixing until the dough forms a ball.

Wrap the dough in plastic wrap and refrigerate for at least 30 minutes.

Flour your work surface and roll the dough out to about 1/8 inch thick.

Cut the dough into rectangles—enough for the top and bottom of the pop tarts.

Place a spoonful of apple pie filling onto one rectangle, leaving space around the edges.

Moisten the edges with the beaten egg, then place another rectangle on top, sealing the edges with a fork.

Preheat your oven to 375°F (190°C).

Gently prick the top of each pastry with a fork to release steam while baking.

Brush the tops with the beaten egg and sprinkle with cinnamon sugar.

Place the pop tarts on a baking sheet lined with parchment paper and bake for 20-25 minutes or until golden brown.

Allow the pop tarts to cool for a few minutes before serving.

Enjoy them fresh out of the oven or at room temperature.