Juliette Binoche, Johnny Depp, Judi Dench, Alfred Molina and Hallström's wife, Lena Olin, star in the film of the book which has turned into a literary phenomenon, transforming the life of the French teacher from Barnsley who wrote it.
Harris, 36, penned the novel after she lost patience with her husband, Kevin, spending nights in front of the television watching football. 'It's what men like doing,' he said. 'Women like eating chocolate.' Less than two years later, Harris has become the North of England's most unlikely purveyor of sex, chocolate and big screen success.
Chocolat has sold in 23 countries worldwide and made the Whitbread Novel of the Year shortlist. It is still in the paperback bestsellers' list - more than a year after it was published - and it is set to stay there for another year when the movie version is released. Only J.K. Rowling's Harry Potter novels have enjoyed greater success.
Chocolat tells the story of a beautiful stranger, Vianne Rocher, played by Binoche, who walks into the fictional village of Lansquenet, between Bordeaux and Toulouse, and opens a chocolate shop in Lent, despite the opposition of the village priest who believes in self-denial.
It is not long before the shop's chocolate 'Nipples of Venus' begin to transform the village. People fall in love, dance and carouse. Vianne, herself, falls for a gypsy called Roux, played by Depp. It is all too much for the pious mayor, played by Molina, who tells Binoche, 'You and your idiot chocolate, get out!'
The theme of the book is transformation and joy. 'There isn't enough around,' Harris said recently. 'I live in Barnsley. If I want gritty realism, all I have to do is look out of my window. People forget that there are simple pleasures out there which are not going to change your life, but are worth experiencing.'
The book did not sell at first, but its popularity spread by word of mouth. Jonathan Rutter of McDonald & Rutter, film publicists, said: 'It was not an instant hit - it was more one of those Wild Swans or Snow Falling on Cedars books. People started talking about it and one day you walked on to a train and there were loads of people - mainly women - reading it.' As its popularity grew, one reviewer asked: 'Is this the best book ever written?'
Chocolat is likely to put Gascony on the map in the same way that Captain Corelli's Mandolin made Cephalonia a literary tourist's hotspot and Thailand's Koh Samui became the place to go for fans of The Beach .
Harris has made enough money to quit her job and spend her time growing her own vegetables and cooking. 'I worry terribly about people who don't eat. They don't know how to live. Like the priest in Chocolat .'
She describes the money she has earned as 'nice' but insists she 'has not acquired bestselling author's behaviour patterns'.
'I'm not one of life's huge livers and spenders,' she says. 'I just buy slightly more of what I bought before. I've got used to having champagne in the house. Every time we get a cheque, we open a bottle.'
Harris is half French, half British. She's been with her husband since they were both at Barnsley sixth-form college. Her latest novel, Blackberry Wine , is - fittingly - about a well-known writer who goes to rural France to discover that there are more important things than material success.
Director Hallström, who made My Life As A Dog and What's Eating Gilbert Grape, earned a clutch of Oscar nominations for The Cider House Rules, including Best Picture and Best Director, last year. Critics say the man who once directed Abba - the Movie is in line for his second nomination with Chocolat .
