Try the Opera, croissants, chocolate croissants, awesome coffee as well (and I am VERY picky!!). Also something typical from back home (France) Pâtes de fruits. If you haven't tried them yet: do it!
The two most exceptional things I've had from here so far are the almond croissants and their brownies. The croissant comes with a delicious custardy paste inside. And the brownies are like truffles!