Creating Ham and Cheese Puff Pastry Hearts is simple if you follow these steps:

1. Preheat Oven: Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
2. Roll Out Puff Pastry: On a lightly floured surface, roll out the puff pastry sheet to about 1/8-inch thickness.
3. Cut Out Hearts: Use a heart-shaped cookie cutter to cut out shapes from the puff pastry. Place them on the prepared baking sheet.
4. Prepare Filling: In a bowl, mix the sliced ham, shredded cheese, and optional Dijon mustard. Season with salt and pepper as desired.
5. Assemble Pastries: Place a spoonful of the ham and cheese mixture in the center of half of the puff pastry hearts. Leave space around the edges for sealing.
6. Top with Pastry: Place a second heart-shaped puff pastry cutout over the filling. Press the edges together to seal. Use a fork to crimp the edges for a decorative touch.
7. Brush with Egg Wash: Brush the tops of the pastries with the beaten egg for a golden finish.
8. Bake: Bake in the preheated oven for 20-25 minutes, or until the pastries are puffed and golden brown.
9. Cool: Allow the pastries to cool slightly on a wire rack before serving.

These steps will guide you in creating these incredible pastries effortlessly.