Dust a work surface with a few tablespoons of flour and roll out your puff pastry so its about a foot long on all sides. Slice the puff pastry into 9-12 pieces depending on how many hot pockets you want to make.
Fill each piece with one slice of ham, a tablespoon of cheese and if you are using mashed potatoes and gravy, a tablespoon of each. Leaving about a centimeter of space around the edges for sealing.
Roll out your second piece of puff pastry and cut into the same amount of pieces as the first. Place each piece on top of the filled puff pastry and seal the edges with a fork by pressing down so the prongs make a mark but don’t tear the dough.
Make an egg wash by whisking the egg with a tablespoon of water. Then brush the tops of the pastries with the egg wash, this helps them get golden brown and flaky in the oven.
Bake the hot pockets 12-15 minutes in the oven until golden brown to your liking. Let them sit 5 minutes before chowing down so you don’t burn the roof of your mouth.