The unnamed woman said the lamington was returned uneaten with a note saying the snack 'doesn't comply with the school's nutrition policy.'
She was also told not to include the popular Australian snack in her child's lunchbox again, despite the fact it only contained around 40 calories.
After sharing the story with 7 News, people were quick to jump to the mother's defence.
'Send a box of lamington's to the principals office tomorrow morning would be my response,' one infuriated person said.
'Schools are pathetic with the garbage they go on with, how dare they tell you what you can & cannot feed your child!' said another.
It comes after a South Australian mother was sent a similar note after sending a slice of cake in her child's lunchbox.