Lulu and Max cafe owner Tessa Flowers-Morrell (left) enjoys an Icey Chocolux shake with chef and food writer Nici Wickes who judged it New Zealand's best shake.

A Hawke's Bay cafe crowned for producing the country's best milkshake came close to closing before winning the award.

Lulu and Max cafe in Hastings beat 304 other contenders to take out the national title with its Icey Chocolux shake, in a competition run by Anchor.

Owner Tessa Flowers-Morrell said the $6 chocolate powder-infused treat had been "flying out the door" over the past few weeks, since being named one of four regional winners of the national competition.

On Tuesday, it was named overall best New Zealand milkshake, beating the other three finalists from Auckland, Whitianga and Blenheim.

Flowers-Morrell, a mother of four who also runs a photography business, said her busy schedule meant she had got to the point where "something had to give" – and it looked like being the cafe.

Then Icey Chocolux was named a regional winner and she thought, "OK, we can't really close now".

"There were just more and more people coming in saying we've got to try this amazing milkshake. Now that we've won the national [title] it's just not going to happen."

The shake combines milk, icecream, chocolate powder and fresh, aerated whipped cream, to create what competition judge Nici​ Wickes described as a "fabulous balance of flavours, not too sweet but it still tasted decadent".

Flowers-Morrell said the secret to the shake's success was the use of chocolate powder, rather than the more standard syrup.

Anchor said the competition, now in its second year, attracted 26,000 votes from around the country, "showing that Kiwis take their milkshakes seriously".

Chef and food writer Wickes made the final decision on an overall winner after the 305 entries were whittled down to four regional finalists.

Icey Chocolux was "my overall favourite, the one I would travel for, the one I could drink on a hot day or a cooler one, the one that left me looking forward to the next time I could enjoy it", she said.

The other finalists were Chocodream, from Auckland's Snacks & Scoops; Woohoo My Mango's Got Pashinit, from Espy Cafe in Whitianga; and Mandarin Chocolate Stracciatella, from Blenheim Railway Cafe & Ice Creamery.