**Instructions**
1. **Preheat & Prep:** Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper.
2. **Slice Croissants:** Carefully slice each croissant horizontally, almost all the way through, leaving a small hinge on one side. This creates a pocket for your fillings.
3. **Fill Croissants:** Open each croissant and layer a slice of ham, followed by a slice of cheese. Close the croissant gently.
4. **Prepare Egg Wash:** In a small bowl, whisk together the egg, milk, a pinch of black pepper, and the optional Dijon mustard until well combined.
5. **Brush & Bake:** Place the filled croissants on the prepared baking sheet. Using a pastry brush, generously brush the tops and sides of each croissant with the egg wash.
6. **Bake:** Bake for 10-15 minutes, or until the croissants are golden brown, the cheese is melted and bubbly, and the ham is warmed through.
7. **Serve:** Carefully remove from the oven. Let cool slightly before serving. Garnish with fresh parsley if desired. Enjoy immediately!
**Short Tips**
* **Cheese Choice:** Don’t be afraid to experiment with different cheeses! A smoky Gouda, creamy Havarti, or even a spicy pepper jack can add a unique twist.
* **Add-ins:** For extra flavor, consider adding a sprinkle of everything bagel seasoning, poppy seeds, or sesame seeds to the top of the croissants before baking. A thin spread of apricot preserves or fig jam inside before adding the ham can also be delicious!
* **Make Ahead:** You can assemble the croissants (without the egg wash) a few hours in advance and keep them covered in the refrigerator. Brush with egg wash just before baking.
* **Reheating:** Leftover croissants can be gently reheated in a toaster oven or regular oven at a lower temperature (around 300°F/150°C) until warm and slightly crispy.
