Cut each square diagonally to give 2 triangles (they will appear quite small). Put the triangle with the wider part facing you and the point away from you.
Break off small pieces of chocolate (approx 1-cm) to place about 2-cm up from the wide end nearest you.
Then carefully roll from that chocolate loaded end towards the point of the triangle.
You should now have something resembling a straight croissant, seal it slightly with your fingertips and curl it around into a crescent.
Place the chocolate croissants on a lined baking tray and paint with the beaten egg. Bake for 15 minutes until golden and puffy and exuberantly, if miniature, croissant-like.