This is cover art for the 8th tome of this series, La lune gibbeuse. You know…
On the surface, nothing distinguishes Isabelle’s life from those of the thousands of her readers. This little girl lives a peaceful life with her aunt Ursule, on the Atlantic coast. And yet, with Delporte, Macherot, Franquin, and Will guiding her destiny, the marvelous is never far away. Ghosts, paranormal powers, or the marriage of her uncle Hermès to the beautiful witch Calendula—anything is possible, and nothing is ever frightening. --BDT
I’ve only read the first book so far, but found it pretty good. It might nominally be considered young adult fare, but I thought it worked perfectly well for an all-ages audience, a neat trick that any series would hope to achieve.
And… that’s it. Here’s one more cover just for fun:
https://www.bedetheque.com/media/Couvertures/Couv_3840.jpg