this is literally an inference:
Ok, so the recipe book that has been passed down for centuries has diary entries that only appear after MC makes something- AKA uses her magic in close proximity. This extremely old recipe book which was evidently a diary before mentioned "Popo and Don" and the two spirts that used to serve the scarlet witch are called Poporoactus and Dontanattez.... So then this diary belongs to the OG witch then-?? and MC is a reincarnation of her??- NICE.