Preheat the Oven: Preheat your oven to 375°F (190°C).

Prepare the Dough: Roll out the puff pastry or bread dough on a lightly floured surface into a rectangle approximately 1/4 inch thick.

Layer the Ingredients: Spread a thin layer of Dijon mustard over the dough if desired. Lay slices of ham evenly over the dough, leaving a small border around the edges. Place the cheese slices on top of the ham.

Roll the Dough: Carefully roll the dough into a log, starting from one of the longer sides. Seal the edges by pinching the dough together.

Prepare for Baking: Place the roll seam-side down on a baking sheet lined with parchment paper. Brush the top with melted butter and then with the beaten egg to achieve a golden crust. Make several diagonal slashes across the top with a sharp knife.

Bake: Bake in the preheated oven for about 25-30 minutes or until the roll is golden brown and the cheese is bubbling.

Garnish and Serve: Remove from the oven and let cool slightly. Garnish with chopped fresh parsley and a sprinkle of salt and pepper.