Ashley finally gets her time to be BIG. Winnie and her become decent friends (much to Muffin's chagrin) so of course the topic of becoming large to tease her best friend would come up with a witch who could potentially make that happen~
She won't become too big, juuuuuust big enough the only evidence of a ferret being nearby is the wiggles under her rump.
Of course, Ash is a sweetheart, so she won't go too overboard with her bigness. She's honestly just happy to have the opportunity to hug her friend more on his level for once <3
And the effect is only temporary, she'll be back to her normal size in a day or two.
Also important to note, because this is an overly silly idea: yes this is canon it's not a silly one-off mwahahaha