We have lovely recipes for croissants. To these, you add chocolate.

Instead of cutting the dough into triangles and rolling into the traditional croissant shape, cut the dough in rectangles, place a Pain au Chocolat stick in the middle and roll them up into the shape of a small pillow. Follow the instructions to bake as for a plain croissant and you'll wind up with a delicious Pain au Chocolate instead of a delicious croissant.

A strip or shards of chocolate cut off a block or even chocolate chips are acceptable substitutes for the Pain au Chocolat stick. Clearly, the better the quality of your chocolate, the better your pastries will taste. And since making croissant dough is quite a bit of work, it is easy to justify the use of high-quality chocolate.