Creating Ham and Cheese Puff Pastry Sticks is straightforward. Follow these steps for delicious results:

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

2. Prepare the Pastry: On a lightly floured surface, roll out the puff pastry sheet to smooth it out, if necessary.

3. Cut the Pastry: Use a sharp knife or pizza cutter to slice the pastry into rectangles, about 3 inches wide and 6 inches long.

4. Mix the Filling: In a bowl, combine the chopped ham, shredded cheese, mustard (if using), and season with salt and pepper. Mix well until thoroughly combined.

5. Fill the Pastry: Place a spoonful of the ham and cheese mixture at one end of each pastry rectangle. Be careful not to overfill to prevent leakage.

6. Fold the Pastry: Carefully fold the other end of the pastry over the filling to create a stick shape. Press the edges together to seal.

7. Prepare for Baking: Beat the egg in a small bowl. Brush the tops of the pastry sticks with the egg wash to give them a beautiful golden color.

8. Bake: Arrange the sticks on the prepared baking sheet, spacing them apart. Bake in the preheated oven for 15-25 minutes, or until they are puffed and golden brown.

9. Cool: Remove from the oven and let cool slightly before serving.

10. Enjoy: These sticks are best enjoyed warm, but they can be stored in an airtight container for later snacking.