Preheat your oven to 400°F (200°C).

Roll out the thawed puff pastry on a lightly floured surface into a rectangle measuring about 12x16 inches.

In a mixing bowl, combine the raspberries, sugar, cornstarch, and vanilla extract. Gently mash the raspberries while mixing but keep some whole for texture.

Spread the raspberry mixture evenly across the center of the rolled-out pastry, leaving a few inches on the edges.

Make cuts on each long side of the pastry, about 1 inch apart, from the edge toward the raspberry filling.

Fold the strips over the filling, alternating sides to create a braided effect.

Brush the top with the beaten egg.

Transfer the prepared Danish onto a baking sheet lined with parchment paper.

Bake in the oven for 25-30 minutes, or until the pastry is puffed and golden brown.

Let it cool for a moment, then dust with powdered sugar before serving.