To a medium saucepan, add the apples, cinnamon, sugar, and butter. Turn the heat to medium and cook until the mixture is bubbly, stirring occasionally.
Cook for 5 minutes until the apple mixture is thick and caramel-colored. Remove from the heat and allow to cool. Add the vanilla.
Preheat the oven to 375 degrees F.
Roll out your puff pastry and cut into 8 equal-sized squares.
Place 2-3 tablespoons of filling in the center of half the puff pastry squares.
Top with a plain pastry square and poke a few holes in the top to allow air to escape. Using a fork, pinch all seams and sides together by pressing lightly all around the pop-tart.
Bake for 20-22 minutes until crisp and golden brown.
Next, make the icing. Mix the sugar and apple juice until smooth.
Once the pop-tarts are cooled, drizzle the icing over the top. Enjoy!