recipe from joythebaker.com

1 package Dufour Puff Pastry (It's the best store bought pastry around.  If you can't find it, go for a brand that uses all butter, and not the fake fat stuff.)

8 slices Prosciutto di Parma

3 Tablespoons Dijon mustard

1 cup Gruyere cheese, grated

flour for dusting

fresh ground black pepper

Preheat oven to 400 degrees F.  Line a baking sheet with parchment paper and set aside. 

Thaw puff pastry in the refrigerator for 2 to 3 hours.  Once thawed, carefully unfold and lay on a floured work surface.  If the pastry tears at the seam in the unfolding process, it's not the end of the world, but try to keep it in one un-torn piece.  Dust flour on top of the pastry as well.

Puff pastry will already be very flat, but with a rolling pin, roll the dough out to about 11x9-inches.  Layer the eight slices of prosciutto on top of the puff pastry.  Using a butter knife, layer the mustard on top of the prosciutto slices.  Top with grated cheese, and as much fresh ground black pepper as you like. 

Begin to roll the right side of the pastry in towards the center.  Next roll the left side of the pastry in towards the center.  Press together.  Dough will not stick together, but if you brush away some of the excess flour on the center dough pieces, they will stay together better during baking.  

With a sharp knife, slice the dough into 1/2-inch thick slices.  Place on a baking sheet lines with parchment paper.  Bake at 400 degrees F for about 12-15 minutes, until a deep golden brown.  Let cool on the pan for 5 minutes, then remove from baking sheet and serve warm or at room temperature.