Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

On a lightly floured surface, roll out the puff pastry sheet to smooth out any creases.

In a mixing bowl, combine the diced ham, cheddar cheese, Swiss cheese, cream cheese, Dijon mustard, and chopped chives. Season with salt and pepper.

Spread the ham and cheese mixture evenly over the pastry, leaving a small border around the edges.

Cut the pastry into your desired shapes squares or triangles work beautifully ensuring each piece holds a generous amount of filling.

Fold or roll each piece to fully enclose the filling, then arrange them seam-side down on the prepared baking sheet.

Brush the pastries with the beaten egg to achieve a gorgeous golden finish.

Bake for 15-20 minutes, or until the pastries are puffed up and perfectly golden brown.