Preheat your oven to 375°F (190°C).
Slice each croissant in half horizontally without cutting all the way through.
Spread 1 tablespoon of Dijon mustard on the inside of each croissant.
Layer 2 ounces of sliced ham and 2 ounces of sliced Swiss cheese inside each croissant.
Close the croissants gently and place them on a baking sheet lined with parchment paper.
In a small bowl, mix the melted butter, garlic powder, dried parsley, salt, and pepper.
Brush the butter mixture over the tops of the croissants.
Bake in the preheated oven for 15-20 minutes, or until the croissants are golden brown and the cheese is melted.
Remove from the oven and let cool for a few minutes before serving.