Wiktionary
n. A French snack consisting of a pastry, normally similar to a croissant, with chocolate inside.
Wikipedia
Pain au chocolat (, Pain de chocolat chocolate bread, also known as chocolatine in the south-west part of France and Canada, is a viennoiserie sweet roll 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 centre.
Pain au chocolat is made of the same layered dough as a croissant. Often sold still hot or at least warm from the oven, they are commonly sold alongside croissants in French bakeries and supermarkets.
Usage examples of "pain au chocolat".
And of course there was Saunders and Gordon back of the Tottenham Court Road with its big squishy sofas and help-yourself bar stacked with pain au chocolat and Danish pastries, loads of different teas and coffee, all the mags and the day's newspapers.