Begin by preheating your oven to 400°F (200°C). Prepare a baking sheet by lining it with parchment paper to prevent sticking.
On a lightly floured surface, gently roll out the thawed puff pastry until it's about 1/8 inch thick. Carefully transfer the pastry onto the lined baking sheet, making sure it's as flat as possible.
Using a sharp knife, lightly score a border approximately 1 inch from the edges of the pastry. Take care not to cut all the way through; this scoring creates a deliciously puffed-up border when baked.
In a large mixing bowl, combine the thinly sliced apples with the granulated sugar, ground cinnamon, fresh lemon juice, and melted butter. Toss everything together until the apple slices are evenly coated in the mixture.
Evenly spread the apple mixture within the scored border of the puff pastry, arranging the slices in a slightly overlapping pattern for an attractive presentation.
In a small bowl, beat the egg, then brush it over the outer edges of the pastry. This helps achieve a beautiful golden finish as the tart bakes.
Place the tart in the preheated oven and bake it for 25-30 minutes, or until the pastry is golden brown and flaky, and the apples have become tender.
Once baked, remove the tart from the oven and let it cool for a few minutes on the baking sheet. This resting time allows the flavors to settle.
For an elegant touch, dust the tart lightly with powdered sugar before slicing. Serve warm with a generous scoop of vanilla ice cream for an indulgent dessert experience.
Notes
Serve warm with vanilla ice cream for an indulgent experience.