Pain au chocolat, also known as chocolatine in the south-west part of France and in French-speaking parts of Canada, couque au chocolat in Belgium, or chocolate croissant in the English-speaking countries, is a type of Viennoiserie consisting of a cuboid-shaped piece of yeast-leavened laminated dough, similar in texture to a puff pastry, with one or two pieces of dark chocolate in the center. The chocolate usually has a slight bite to the texture. Pain au chocolat is made of the same layered dough as a croissant. Often sold still hot or warm from the oven, they are commonly sold alongside croissants in French bakeries and supermarkets.

Source: Wikipedia