Preheat your oven to 375°F.
Slice each croissant in half horizontally, creating a top and bottom.
Spread 1/2 tablespoon of Dijon mustard on the inside of each croissant half.
Layer 2 ounces of sliced ham and 2 ounces of sliced Swiss cheese on the bottom half of each croissant.
Place the top half of the croissant back on.
In a small bowl, mix together the melted butter, garlic powder, dried parsley, black pepper, and salt.
Brush the butter mixture generously over the tops of the croissants.
Place the croissants on a baking sheet lined with parchment paper.
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.