SOLVED. Dark Fantasy- Girl is apprenticed and later married to (possibly) evil sorcerer. Spoilers ahead.

[Maya]

Edit: SOLVED! Sorrow's Child by Georgina Anne Taylor.

I read this book around 2012-2015. The girl is forced into working for the sorcerer, making tinctures and potions etc. I think she also had some magical ability. He forces her into marriage, and somewhere along the way she realizes he’s evil. At the climax she pretends to submit to the marriage and makes dinner for him, but she had poisoned every part of the meal. As he’s dying, she chops off his hand and makes a hand of glory, eventually using it to blow up his house. Other details: He’s fond of some sort of candied fruit, that’s where most of the poison was. I think she summons a swarm of flies at the climax? That’s all I remember, thanks in advance!