A Face Like GlassA Face Like Glass by Frances Hardinge. The girl's name is Neverfell.
Per https://en.wikipedia.org/wiki/A_Face_Like_GlassWikipedia:
In the underground city of Caverna, craftsmen are able to create items with magical properties, such as cheese that gives you visions of the future, a wine that can remove or restore memory, or perfumes that can control the thoughts of whoever detects it. Citizens born in Caverna have no problems feeling emotions but lack the ability to display them on their faces, and must be taught each expression by craftsmen known as facesmiths. The book follows Neverfell, the apprentice and adopted daughter of the cheesemaker Grandible, as she becomes entangled in a net of conspiracies and betrayal. Neverfell is not like the other inhabitants of Caverna, for her face shows exactly what she is feeling and thinking, being unable to lie in a world where everything is built on lies.
