Preheat oven to 400°. Line two baking sheets with parchment paper and set aside.
Roll out dough* and using a round cutter, cut shapes in 3" rounds.
Spread with a small amount of mustard and sprinkle half the dough with ham and cheese leaving a 1/4" border around the edge of the dough. Brush the edge of the dough with water, fold over and crimp edges with a fork. It's best to freeze the empanadas and cook from a frozen state. Freeze individually on a baking sheet and then store in a freezer tight bag. If you don’t have time to freeze then bake, refrigerate them until they are very cold, about 1 hr.
Brush the egg/water mixture over top of the dough and bake for 15 min or until crust is lightly browned. If baking from a frozen state it may take 25 minutes to baking.
*Keep puff pastry as cold as possible, if dough begins to stick return to the refrigerator until cold and then continue with recipe.