Kiwis expressed their disappointment on social media within one saying the design was "not an Easter Egg."
"When is an Easter Egg not an egg? Answer - when it's only half an egg," a loyal customer and chocolate lover told the Herald.
"And to make matters worse it's no longer foiled - it's wrapped like a chocolate bar - way to spoil Easter Hunts for Kiwi kids. Who are they kidding?"
Cadbury has since been flooded with hundreds of comments asking them to consider reverting to the original marshmallow egg shape and taste.
However, Cadbury says this is not possible.
"Cadbury Marshmallow Eggs will take on a new shape this Easter, but they will still have the same marshmallow fluffiness and yolk that Kiwis love, and they'll continue to be covered in delicious Cadbury chocolate," Cadbury senior marketing manager Mel Yates told the Weekend Herald.
"While we would like to have continued making them the same shape, the age of the previous equipment has meant we've invested in more modern equipment which will ultimately deliver more consistent quality.
"The new shape was actually developed by our Dunedin team, and a number of members of that team have relocated to Melbourne with their families to continue overseeing production of the Cadbury products they love including Marshmallow Eggs. It's a change that would have happened anyway, the factory closure just brought the timing forward.
"As with any change, some people will be disappointed by the new shape, but we hope they'll give them a try as we're confident Cadbury Marshmallow Eggs will continue to be one of New Zealand's favourite Easter treats."
