Furious Cherie Williams, 26, poured little Charleigh’s tea time treat onto a plate to find the bottom of the container was covered in green SLIME.
The mum-of-one said staff dismissed the stain inside the £1.99 snack box as grease residue despite its unnatural colour.
It was bought by grandma Mandy, 52, who takes Charleigh to the fast food restaurant in Bulwell, Nottingham once a week.
Shockingly, Mandy said that a supervisor LAUGHED at her when she returned the next day to complain.
It was only after being approached for comment the restaurant chain reversed its position and offered to compensate the family.
Cherie said: “Usually I just give it her in her box, but luckily enough I tipped it out and the box was all green and mouldy.
“My daughter had asthma as a baby and the doctor always said mould spores affect people with asthma even more so than other people.
“They didn’t even offer a £1.99 refund, or a replacement meal, not even an apology at first. It was disgusting.
“I tried the KFC customer careline but I couldn’t get through, the longest I was on hold was 45 minutes before I gave up.”
Grandma Mandy added: “The supervisor said the markings were just grease.
“I’m just so mad, she was just patronising and laughing and saying ‘it’s just where the chicken’s been’.”
A KFC spokesperson said: “We’re very sorry for this as we don’t want any of our customers to have a bad experience in any of our stores.
“We have never had an issue like this before and are carrying out a thorough investigation to make sure that it is an isolated incident.
“Our customer care-line will be in touch with Miss Williams to offer her a gesture of goodwill.”