Help me please find this

Hellooo!! A long while back I read this manga of a princess and her friend who was her poison food taste tester. This guy is I think hella good at medicinal stuff and has this silver hair due to the testing?training? he had to endure to become this dude impervious to poison. She was like this knight/general-esque princess. That’s all I can remember if anyone knows I’d appreciate it so much if you could help a girl out!! Ty! ٩(๑❛ᴗ❛๑)۶