Preheat the oven:
Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper to prevent sticking.
Prepare the puff pastry:
Roll out the puff pastry on a lightly floured surface. If using store-bought pastry, it will usually come in a square or rectangular shape. Gently roll it out into a rectangle of about 12×9 inches (or according to the size of your sheet).
Assemble the pinwheels:
Spread a thin layer of Dijon mustard (if using) over the puff pastry. Evenly distribute the sliced or diced ham over the pastry, leaving about 1 inch from the edges. Sprinkle the shredded cheese evenly over the ham.
Roll the pastry:
Starting from one edge, carefully roll the pastry into a tight log, similar to making a jelly roll. Be sure to roll it as tightly as possible to ensure even pinwheels. Once rolled, seal the edge by pressing lightly to close it.
Slice the pinwheels:
Using a sharp knife, slice the rolled puff pastry into 1-inch wide pieces. You should get about 8-10 pinwheels depending on the size of your roll.
Prepare for baking (optional egg wash):
If you want a golden, glossy finish, whisk the egg in a small bowl and brush it lightly over the tops of each pinwheel. This step is optional but adds a lovely shine and helps the pinwheels develop a beautiful golden color when baked.
Bake the pinwheels:
Arrange the pinwheels on the prepared baking sheet, leaving a little space between them. Bake for 15-18 minutes, or until they are golden brown and crispy.
Serve:
Once baked, remove the pinwheels from the oven and let them cool for a couple of minutes. Serve warm, garnished with fresh herbs if desired.
