Creating Ham and Cheese Pockets is straightforward. Just follow these step-by-step instructions:

1. Preheat your oven to 400°F (200°C).
2. Roll out the puff pastry sheets on a lightly floured surface. Cut each sheet into equal squares, approximately 4 inches by 4 inches.
3. In a mixing bowl, combine diced ham, shredded cheese, and mustard (if using). Season with salt and pepper to taste.
4. Place a spoonful of the ham and cheese mixture into the center of each pastry square.
5. Fold the pastry over the filling to form a triangle or rectangle, sealing the edges with a fork.
6. Beat the egg in a small bowl to create an egg wash. Brush the tops of the pockets with the egg wash for a golden finish.
7. Place the filled pockets on a baking sheet lined with parchment paper.
8. Bake in the preheated oven for 15-25 minutes, or until golden and crisp.
9. Remove from the oven and allow them to cool slightly before serving.

These simple steps ensure you create delicious, flaky ham and cheese pockets without any hassle!