01 -
Preheat oven to 400°F. Line a baking sheet with parchment paper and lightly dust work surface with flour.
02 -
Unfold puff pastry sheets on floured surface and gently roll each to approximately 1/8 inch thickness, maintaining delicate layers. Refrigerate if pastry softens.
03 -
Place one pastry sheet on baking sheet. Evenly arrange ham slices, leaving a ½-inch border. Layer cheese slices atop ham. Spread Dijon mustard over cheese if using.
04 -
Cover with second pastry sheet; press edges gently to seal. Crimp edges with fork to secure filling. Brush entire top surface with beaten egg wash.
05 -
Bake 20-25 minutes until pastry is puffed, golden brown, and crisp. Tent with foil if browning unevenly.
06 -
Cool on baking sheet 5 minutes to stabilize, then slice into 8 portions. Serve warm with melted cheese.