Begin by thawing the puff pastry according to the package instructions. Once thawed, lightly flour your work surface and roll out the pastry to smooth out any creases. Cut the pastry into four equal squares.

In a microwave-safe bowl, combine the chocolate and heavy cream. Heat the mixture in 30-second intervals, stirring after each, until the chocolate is completely melted and smooth, about 1-2 minutes. Let it cool slightly.

Take one pastry square and place about 1 tablespoon of the chocolate mixture in the center. Spread it gently, leaving a small border around the edges.

Fold each pastry square diagonally to create a triangle. Pinch the edges together firmly to seal, then crimp with a fork for a decorative touch.

In a small bowl, whisk together the egg and water. Brush this egg wash over the tops of the turnovers.

Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper and arrange the turnovers, leaving space between them. Bake for 15-20 minutes until golden brown.

Let the turnovers cool for a few minutes on the baking sheet before serving warm or at room temperature.