Mr Poipoi puts the success of the pudding down to using real ingredients - real butter and real milk.
"The plum jam pudding mixed with the butter makes it addictive. It's popular and people come back and get more and more.
"The comment we get is that it's luxurious - quite decadent."
Since opening two years ago the business has built up a big reputation for its popular supplies of fried bread, hangi meals, boil ups, seafood chowders and rewana bread.
At first Kiwi Kai sold 30 puddings a week. It now sells 1000 a week.
A spokesperson for The Mad Butcher confirmed Kiwi Kai was an approved supplier.
The Amohau St business' pudding was developed from a family recipe and although "mum's didn't quite work", with a little tweaking and tasting it's been adapted for commercial consumption, while still retaining its original home-baked artisan taste.
Mr Poipoi thinks the runaway success is due to the niche market he's created, which is Maori baking. And it's not just the steamed pudding that has developed a loyal following.
"The big waha nui burger is loaded with half kilo and layers of meat - it's a big burger - that's what makes the difference and people come back for more," he said.