Here's one for all you fanatical Messina fiends. The inventive minds behind the cult gelato chain and iconic Australian biscuit company Arnott's have done the patriotic thing for Australia Day and put their heads together to come up with a range of tongue-tripping Tim Tam flavours.

The new biscuit line, concocted in Arnott's western Sydney command centre, comprises four gelato-inspired flavours: choc mint for the traditionalists; black forest for something rich and delectable; coconut and lychee for the adventurous of appetite; and salted caramel with vanilla, of course, for die-hard Messina fans.

The proposal from Arnott's for the collaboration came as a surprise to the Messina team, says a cofounder of the chain, Declan Lee.

"We just assumed they were going to send us a nasty cease-and-desist letter and tell us to stop making our Tim Tam slam flavour, which we made without permission," he says.

"On the contrary ... they wanted us to start testing to see if we could make some Tim Tam flavours, which was pretty exciting."

But the project was not without its challenges for a team more accustomed to churning milk and sugar, Lee says. The aim was to reproduce gelato flavours in buttercream form in a way that also worked with chocolate.

"Making an ice-cream is one thing - and making a biscuit that tastes like that ice-cream is a whole other story," he says.

Tim Tam Inspired by Gelato Messina goes on sale in supermarkets nationally from February 6 for $3.65