Deborah Harkness All Souls series begins with

A Discovery of Witches. Finished it yesterday and started Shadow of Night (book two). Book Three to be publushed this July.

Very engaging writing, carefully considered weaving of the plot of an academic witch historian doing research in alchemy, reading very old manuscripts. The author, an historian, references an assortment of old writings herself. There is a romance started with a very old vampire, and other witches and daemons are included. There is a mystery of incredible consequence to be solved, a war amongst magical creatures is started. It's fun, interesting, and not juvenile.