Chocolate may not be the first thing that comes to mind when one thinks of Vietnam.

Yet in recent years, five-year-old artisan chocolate brand Marou Faiseurs de Chocolat from Ho Chi Minh City has been making waves worldwide. It has been written about in The New York Times and Forbes.com, and Marou's single- origin dark chocolate bars are sold everywhere from Britain to Thailand.

But the brand came about because of boredom. French-Japanese Samuel Maruta, 42, had ditched his job in banking and was itching to do something "more fun".

He met Frenchman Vincent Mourou, 44, in 2010, when both were based in Ho Chi Minh City. Mr Mourou had left his advertising job. The like-minded duo realised they shared a passion for cacao, and became business partners.

They had considered going into coffee as Mr Maruta has connections with coffee farmers in Vietnam. But, observing that chocolate was an untapped market in the country, they went the cocoa route instead.

They started to get in touch with cacao farmers with the help of their coffee connections.

On the brand's early days, Mr Maruta says: "We started tinkering with chocolate at home. We would roast beans in the oven and grind them with a blender. But the chocolate would always be gritty."

Marou's beginnings also resulted in a detour to Singapore.

Looking for a machine to achieve a smoother texture, Mr Maruta realised that using a stone grinder would work best. "We figured that since Indian cuisine uses stone grinders for their spices, we should go to an Indian restaurant to find one. The owner directed us to Singapore, to Mustafa Centre in Little India," says the father of two daughters aged 13 and 11.

Since then, Marou - a combination of Mr Maruta and Mr Mourou's family names - chocolates have been ground with 15 industrial- sized stone grinders. One grinder produces about 25kg of chocolate.

The chocolate bars are labelled according to the province the beans come from, such as Tien Giang, Dong Nai and Ba Ria - all in southern Vietnam.

To cater to the surge in demand, production capacity will be increased. Mr Maruta says: "We now do 100kg of chocolate a month and can go up to three tonnes."

They work with 15 farms and started an "experimental plantation" last year by planting 2,500 cacao trees as the land owner wanted to attract tourists. Mr Maruta says: "The owner wanted to clear out all the trees and plant rubber ones. But then, rubber trees aren't exactly very sexy for people to visit. However, people like cacao."

Calling it a "long-term investment", he adds that they will see results only in 2020.

It is still very much a learning journey for them.

Mr Maruta gives the example of the limited-edition Treasure Island bar, made with cacao from the Tan Phu Dong island in the middle of the Mekong River. He says that last year, the area suffered from bad drought and sea water flowed upstream instead. Trees died and the harvest was poor.

The chocolate-makers are also busy doing collaborations.

Mr Maruta was recently in Singapore for the launch of exclusive Marou chocolates in partnership with Gallery & Co in the National Gallery Singapore and Ho Chi Minh-based creative agency Rice Creative.

It has been a year in the making and began when he visited Singapore last year. He was taken on a private visit to the museum before it opened and got inspired by the tree-like beams, black-and-white marble tiles on the former Supreme Court foyer and the dappled light that shines through the reflection pools on the roof of the City Hall building. These are reflected in the packaging of the bars.

The pack of three chocolate bars - plain dark chocolate, sea salt and candied chilli pepper - costs $29.90 and is sold exclusively at Gallery & Co. The rest of Marou's collection can be bought at Hello Chocolate's kiosk in Pedder on Scotts at Scotts Square.

Mr Maruta has also been busy with the new Maison Marou, which opened in Ho Chi Minh City in May. The cafe sells the brand's chocolate bars as well as bon bons, pastries and drinks.

On their journey so far, he says: "We are riding the wave of the bean-to-bar trend. Five years ago, I would have to explain what the trend is and about single-origin chocolate. Now, people are getting used to trying chocolate from diverse places. They start to appreciate our work."

• The Marou & Co chocolates trio pack ($29.90) is exclusively available at Gallery & Co, National Gallery Singapore, 1 St Andrew's Road. For the rest of the Marou chocolate collection, go to www.hellochocolate.asia or its kiosk at Pedder on Scotts, 6 Scotts Road, Scotts Square, Level 2.