Zumbo sold more than 5000 macarons in three days, quadruple the normal rate, at his Balmain patisserie following last Monday's broadcast of his 120-piece creation of raspberry-beetroot and black olive macarons.

''It's pretty crazy; it's just a constant queue,'' he said.

''Anything we send to the shop, macaron-wise, it's gone. We take three of four loads up every day.''

Staff have been putting in 18-hour days, with queues of 40-plus customers spotted lining up outside the Darling Street shop.

Even though it is the fifth challenge Zumbo has set on the show, ''this is the most crazy it has been''.

''The croquembouche was crazy. And then the mousse cake was crazy, massively crazy, but we just couldn't keep up with that number of mousse cakes. About 4000 people wanted a mousse cake and I was like, well, 'Where am I going to make those mousse cakes?' This time we tried to get ready but we just can't keep up with the macarons. We're piping all day, and I worked until midnight last night just piping macarons with one of the guys.''

With the finals drawing closer, Zumbo has his pick for who will win.

''My money is on Adam or Jimmy.''