Preheat the oven to 425ºF.
Roll out one sheet of puff pastry to about a 12-inch square. Brush lightly with mustard. Add one layer of proscuitto, sprinkle with Asiago or Parmesan cheese. Roll up and seal the edge with egg wash. Freeze the rolls for about 1 hour or until firm enough to slice. Cut into small disks, about one-fourth inch thick and bake at for 10 to 15 minutes on a baking sheet lined with parchment paper.
Unused rounds can be frozen uncooked and baked in the future.