An Otago couple whose three-year-old son was served raw chicken nuggets on Saturday morning were left fuming at the restaurant's alleged response.
But the fast food chain, which has taken full responsibility for the "human error", has said staff handled the incident appropriately and a full investigation is underway.
Hayden Todd and his partner Jemma Wishart, both 22, ordered their son Eli a Happy Meal from the Anderson's Bay joint.
Eli was two nuggets down when Ms Wishart realised something was wrong, Mr Todd said.
"My partner grabbed a nugget and took a bite and thought, 'What the hell?'" he told Newshub.
Photos provided to Newshub show pink, visibly raw chicken inside the nuggets.
"It was not even attempted to be cooked," Mr Todd said.
"It was completely raw. Stone cold."
The pair have been watching Eli "quite fiercely" since he ate the McNuggets - but claim McDonald's didn't seem quite so concerned.
"I rang them up and they weren't even interested over the phone. I went back and got told there's no point in getting angry about it. That just made me any angrier," Mr Todd said.
"They said to take him to a doctor if we were worried.
"They offered my money back... but only for the Happy Meal, not the whole meal. I threw it back at them and said don't worry about it."
But McDonald's spokesman Simon Kenny told Newshub staff offered to pay for any medical costs to take Eli to see a doctor.
"As soon as the customer contacted the restaurant staff checked and there were no other undercooked nuggets," Mr Kenny said in a statement.
"Several members of staff spoke with the customer, who was understandably upset with the mistake.
"Staff and our franchisee offered to refund the meal and to cover any medical costs."
Mr Kenny said food safety is of "utmost importance" and detailed training, food handling processes and food safety checks are in place.
"Unfortunately in this case there was human error with the staff member taking the nuggets out of the fryer early," he said.
"As per our health and safety processes the restaurant is completing a full investigation and is following up with staff."
But Mr Todd said he'll be taking his complaint further, suggesting taking it to the Ministry of Health.
"It's pretty pathetic. It's a kids' Happy Meal, you think they'd remain priority," he said.
"[McDonald's] are trying to make out they care but it didn't sound like they were too bothered."