Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper or a Silpat for easy cleanup.

On a lightly floured surface, unfold the thawed puff pastry into a rough 9×12-inch rectangle. Gently roll to even thickness, about 1/8 inch.

In a medium bowl, whisk together pumpkin puree, brown sugar, pumpkin pie spice, heavy cream, vanilla, and sea salt until smooth.

Cut the pastry into 6 equal rectangles (about 4×6 inches each). Leave a ¼-inch border free of filling. Use a small spoon or offset spatula to spread 2 tbsp of pumpkin mixture on each piece.

Beat the egg with 1 tbsp water to make an egg wash. Brush the pastry borders with egg wash, then fold each rectangle in half lengthwise, pressing edges with a fork to seal.

Using a sharp knife, make two small slits on top of each pastry to release steam. This helps keep the layers flaky.

Transfer to the prepared sheet and bake on the middle rack for 18–22 minutes, until puffed and golden brown. Keep an eye on the edges—they brown faster.

Let pastries rest on the pan for 5 minutes before transferring to a wire rack. Optional: dust with powdered sugar or drizzle with a simple glaze made from ½ cup powdered sugar + 1–2 tsp milk.