Follow these uncomplicated steps to create your Baked Ham and Cheese Croissants:

1. Preheat Oven: Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
2. Prepare Croissants: Cut each croissant in half lengthwise, creating a top and bottom.
3. Assemble the Filling: Spread a thin layer of Dijon mustard (if using) on the cut side of each croissant.
4. Layer the Ham: Place a generous portion of sliced ham on the bottom half of each croissant.
5. Add Cheese: Top the ham with a hearty amount of shredded Swiss or cheddar cheese.
6. Close the Croissants: Place the top halves of the croissants back on top of the fillings.
7. Melted Butter Mix: In a small bowl, mix together melted butter, garlic powder, and dried parsley or Italian seasoning.
8. Brush on Topping: Using a pastry brush, generously coat the top of each croissant with the melted butter mixture.
9. Season: Sprinkle with salt and pepper as desired.
10. Bake: Place the assembled croissants on the lined baking sheet and bake in the preheated oven for 15-20 minutes, until the croissants are golden brown and the cheese is melted and bubbly.
11. Cool: Remove from the oven and let cool for a few minutes before serving.

These simple steps will guide you toward a rewarding and delicious culinary experience.