1. Prepare the Oven and Baking Sheet:

• Preheat oven to 425°F (220°C).
• Line a cookie sheet with parchment paper.

2. Make the Béchamel Sauce:

• In a small saucepan, melt 2 tbsp butter over medium heat.
• Add 2 tbsp flour and stir constantly for about 3 minutes until smooth and bubbling.
• Gradually whisk in 1 cup milk and cook for about 5 minutes, stirring until thickened.
• Remove from heat and stir in 1 ½ tbsp Dijon mustard. Season with salt and pepper to taste.

3. Prepare the Puff Pastry:

• Roll out the puff pastry into a 13 x 15-inch rectangle on a lightly floured surface.
• Cut into rounds using a 2-inch biscuit cutter.
• Use a smaller cutter to score a circle inside each round without cutting all the way through. Poke the center of each round with a fork.

4. Assemble the Rounds:

• Brush the edges of the rounds with the beaten egg mixture.
• Top each round with:
  • ½ tsp béchamel sauce
  • Chopped ham
  • Shredded Gruyere cheese
• Sprinkle with a dash of pepper.

5. Bake the Pastries:

• Place rounds on the prepared cookie sheet.
• Bake for 15 minutes, or until the pastries are golden, puffy, and the cheese is melted.

6. Serve:

• Allow the pastries to cool slightly before serving. Enjoy warm for the best flavor.