A Curse of Ash and Embers by Jo Spurrier

Some people knit socks by the fire at night. Gyssha Blackbone made monsters. But the old witch is dead now, and somehow it’s Elodie’s job to clean up the mess. When she was hired at Black Oak Cottage, Elodie had no idea she’d find herself working for a witch; and her acid-tongued new mistress, Aleida, was not expecting a housemaid to turn up on her doorstep.

Gyssha’s final curse left Aleida practically dead on her feet, and now, with huge monsters roaming the woods, a demonic tree lurking in the orchard and an angry warlock demanding repayment of a debt, Aleida needs Elodie’s help, whether she likes it or not. And no matter what the old witch throws at her, to Elodie it’s still better than going back home.