Preheat oven to 180°C. Line 2 baking trays with paper.
Roll out puff pastry and cut into 8 equal squares.
On each square place a slice of cheese. Top with salmon and 2 or 3 asparagus spears.
Fold 2 corners of the pastry into the centre and press together to seal.
In a small bowl, whisk the eggs with a fork and brush over the pastries.
Bake for 20 minutes, until golden. Serve hot.