Barefoot Contessa's Ham and Cheese in Puff Pastry

I made this recipe for a friend's 40th birthday party a year ago, and I remember it being such a hit that I decided to make it again for a White Elephant Christmas party. I think Ina Garten hit the nail on the head with this appetizer. I love me a ham and cheese sandwich, but adding puff pastry to the mix just takes this rather plain sandwich to another level. Also, substituting gruyere cheese in place of swiss cheese makes it even fancier. And, using Dijon mustard instead of plain ol' yellow mustard takes it to gourmet status. Plus, it's super simple to make and tastes yummy! Really. Give this fancy version of the plain ol' ham and cheese a try and you will want to make it for your next party! Enjoy!

Ingredients:
1 package (2 sheets) frozen puff pastry, defrosted (recommended: Pepperidge Farm)
2 tablespoons Dijon mustard
1/4 pound black forest ham, sliced
1/2 pound Swiss Gruyere cheese, sliced
1 egg, beaten with 1 tablespoon water, for egg wash

First, roll out your puff pastry so that it's around 10 by 12 inches. If you have trouble rolling it like I did then just skip this part. The sandwich will still taste the same. Next, spread the dijon mustard on the puff pastry, but leave space around the edges. Then, add the ham and then the cheese. Brush the border with the egg wash. Be sure to roll out the second puff pastry to 10 by 12 inches or just leave it as is, but either way you need to place this on top of the filled pastry. Pinch the edges together to help seal the two puff pastries together. Gently, brush with the egg wash and slice small slits so that steam can escape while baking. Place a piece of parchment paper on a baking sheet, and then gently move the puff pastry to the baking sheet. Bake at 450 degrees for 20 to 25 minutes or until the pastry is a lovely golden color. Serve hot or warm.