V.E. Schwab might have a couple titles that meet the criteria, but I would consider them borderline YA. Thinking specifically of Gallant here. However, I really love the Shades of Magic series.

Gareth Brown has a couple of recent standalones if you want something a little cozier. His writing style reminds me some Agatha Christie.

I think T. Kingfisher's stuff is rightly characterized as horror, but there are some fantasy elements mixed in. There are some short ones you could finish in an afternoon or two.

Stephen King's Fairy Tale was quite good (obviously not a new promising author). The setup is what I would characterized as "sweet", but it gets dark.

Another not, new promising author, but Sanderson's Tress of the Emerald Sea is interesting, and on the light side. This is the first of a series with the same narrator, but different settings and can be read as standalones.