Look at the title. What's not to like?! This would make a great appetizer for Thanksgiving or a holiday party. Puff pastry has always intimidated me but this was actually really easy and the final product looks pretty impressive. This is adapted from an Ina Garten recipe - she used soppressata and all gruyere whereas I made it with prosciutto and half mozzarella since gruyere can be a little overwhelming for my taste. You could really do any meat and cheese combination here and I think it would be hard to go wrong.
1 package frozen puff pastry (2 sheets) defrosted - I used Pepperidge Farm
2 tsp. dijon mustard
3 oz. prosciutto
3 oz. gruyere cheese grated
3 oz. mozzarella grated
1 egg or 1 tbsp butter, melted (for wash)
Preheat oven to 450 degrees. Cover a baking sheet with parchment paper. Take one sheet of the defrosted puff pastry and roll it out on a floured surface (put some flour on the rolling pin too!) so it is about a 10 inch square. Don't worry if it isn't perfect - you will trim the edges later. Place it on the parchment paper-lined sheet. Brush the pastry with the mustard, leaving a half inch border bare.
Lay the prosciutto on top of the mustard. Brush the border with melted butter or the beaten egg and a little water (I used butter because I was out of eggs, Ina recommends egg). Sprinkle with both cheeses. Roll out the other sheet of puff pastry and lay it directly on top of the cheese covered one. Brush the top of that one with the rest of the butter or egg wash.
Chill in the refrigerator for 15 minutes or the freezer for 5 minutes so the pastry is firm.
Trim the edges so they are straight and cut three slits across the top of the pastry so that the steam can escape. Bake for 20-25 minutes until golden brown. Let it cool slightly before cutting into squares. Serve warm.