How should you call this flaky, chocolatey pastry you order at a café? Well, depending on who you ask, you'll get a different response.
Ask any Parisien and they will tell you, it is a pain au chocolat. No hesitation. But hold on a minute. Even in France, where it is a staple breakfast or snack much like the donut is to Americans, disagreement is rife. While most of France does call it un pain au chocolat, in the South-West, they endearingly refer to it as une chocolatine. And so do their trans-atlantique cousins, the Quebecois. But wait, more dissidents can be found in the francophone parts of Belgium, such as Brussels, where they call it une couque au chocolat. To make matters worse, ask any American, and they will tell you its a chocolate croissant...! *Audible gasps from any Francophone person reading* Yes, you read that correctly.
While it may be made with the same type of pastry as a croissant, many would rightfully argue that a croissant is called a croissant because of its crescent shape and thus cannot be appropriated for its square shaped sibling. To add insult to injury, the ignorant will correct how you refer to the delicious little pastry when ordering it with a "oh, you mean a... ". However frustrating it may be, rather than giving geometry lessons, let's check our pride at if you want the door and simply adopt what the locals say! It doesn't make it any less tasty ¯\_(ツ)_/¯
For more on this topic, enjoy this short video documentary interviewing les Français on how they prefer to call it.