Preheat oven to 400 degrees. Line 2 large baking sheets with Silpats or parchment paper.
Defrost puff pastry according to package instructions, about 30-40 minutes.
Gently unfold 1 pastry sheet and place on a lightly floured surface. Use a lightly floured rolling pin to flatten out the creases.
Spread 1/2 the mustard evenly over surface, leaving a 1/2 inch border. Sprinkle 1/2 the rosemary evenly over mustard. Arrange 1/2 the salami slices over mustard, overlapping as needed. Sprinkle 1/2 the cheese over salami. Brush plain border with beaten egg. Roll up pastry, jellyroll fashion, pressing to seal seam. Repeat with remaining pastry, mustard, rosemary, salami and cheese. Cut logs crosswise into 1/2-inch-thick rounds. Arrange rounds on prepared sheets, spacing 1 inch apart. Brush tops of rounds with egg.
Bake in preheated oven for 18-20 minutes or until nicely golden brown. Serve warm.