Preheat your oven to 425°F (220°C) and line a sheet pan with parchment paper.

On a floured surface, roll the thawed puff pastry into a large rectangle until it's about double its original size.

Cut the pastry into 6 squares, ensuring the edges are squared off.

Toss the trimmed asparagus with extra virgin olive oil and season generously with salt and pepper.

Lay a slice of prosciutto on each pastry square, folding it in half for a better fit.

Place 3-4 stalks of asparagus on top of the prosciutto, depending on their size, followed by 1-2 tablespoons of Gruyere cheese.

Fold two opposite corners of the pastry over the asparagus, pinching the seams to seal.

Brush the tops with the beaten egg and sprinkle with additional salt and pepper as desired.

Bake for 12-15 minutes, or until the pastry is golden and puffed.

Serve hot or at room temperature.