There's always been a rivalry between French, Belgian and Swiss chocolatiers. But France can lay serious claim to having perhaps the celebrated chocolate tradition - they invented the truffle, after all. Headed by Gilles Marchal, a former pastry chef at the Plaza Athenee and Le Bristol hotel, today he is showing us around the company's Nanterre headquarters, situated in a non descript suburb in the hinterlands of Paris' industrial estates.

Before you enter the factory floor, the air is dizzyingly heavy with the nutty aroma of cocoa - it's so cloying, you want to faint from the languid smell. And it's all understandably clinical: a careful and ritualised ablution must be performed, where scrubs are worn to prevent any unwanted human detritus from mingling with the delicate production process.

Of course, that's all extraneous once you actually step foot on the floor. The heavy aroma gives away to light tropical notes - a reminder of the chocolate's exotic origins in Madagascar, Ghana or the Caribbean. Marchal sources his chocolate from Valrhona, a French chocolate-maker considered to be one of the best in the world who supplies its 'couverture chocolate' - a high quality form which uses the best chocolate beans.

Marchal prefers its Grand Cru chocolate, a method Valrhona championed in the 1980s that treats the cocoa beans like wine. He understands all the various components, from soil to microclimate, that might affect the final flavour of the couverture. Couverture made from beans in Madagascar in one year will differ from those from the same source in another.

Marchals tells me he often likes to blend Grand Cru couvertures, which can affect the taste of the chocolate. 'It's not just about the product, but about the recipes,' he says. They use 20 different types of chocolate and create a mix from these.

Valrhona chocolate is known for its light, floral notes which take on the flavours Marchal likes to use: mint, black tea, cinnamon and even whisky. The flavours are never added to the melted chocolate, but are infused with cream so that they mix better.

He urges us to try from a vats of carefully melted ganache in different flavours, which is the mixture formed when cream is combined with the melted couverture. In chocolate parlance, the ganache is the backbone of any piece of chocolate - Le Maison creates four of them per day by using 30-50kg of chocolate.

As we push onto the next room, it's a serene scene where long corridors of melted ganache stretch from one end of the room to another on morgue-like steel-tables. The closest comparison we can think of is nap-time at a kindergarten, an apt metaphor as the chocolate requires lots of resting before it can be cut or decorated.

The optimal temperature must be maintained between 10-12 degrees, and once the chocolate has been cut on a 'guitar', it is taken through to the 'enrobing room' where it is hand-decorated - on our visit, three people were individually responsible for placing red dots on a batch of chocolates, simply for decorative effect. These decorating tasks change throughout the day, depending on the nature of ornamentation.

When it's time for quality control, it's a remarkable scene that draws our envy: conveyors belts of chocolates running down the length of the room, while nonchalant workers handle and check if there are any final flaws, while carelessly discarding chocolates that don't fit the bill.

We leave with a box of chocolate and Portuguese poet Fernando Pessoa's timely quote in our head: 'Look, there's no metaphysics on earth like chocolates.'

MORE TREATS

Rococo

English chocolatier Chantal Coady stresses the homemade with her chocolates, with flavours ranging from Basil to Persian lime. She creates ethically traded and sourced chocolates made from organic cocoa beans and uses it in all her products. rococochocolates.com

Jean-Paul Hevin

French master chocolatier Hevin's couvertures are made from beans grown in Venezuela, Ecuador, Colombia and Madagascar. Their esteem is such that they recently launched Hong Kong's first Parisian-style Boutique et Bar a Chocolat on Lyndhurst Terrace in Central, with exclusive coffret boxes and luxurious hot chocolate. jphevin.com

Valrhona

As well as being one of the most famous suppliers to brands, Valrhona produces three vintage chocolate varieties under its own name - Ampamakia, Gran Couva and Palmira - each made from beans grown in Madagascar, Trinidad and Venezuela. valrhona.com

L'Artisan du Chocolat

A newer chocolatier on the scene, L'Artisan only started up in 2001 but are acclaimed for their ganache-filled chocolates and liquid salted caramels, with exclusive flavours like Japanese Green Tea Matcha. lartisanduchocolat.net

Charbonnel et Walker

Charbonnel started out in 1875 through the encouragement of King Edward VII. They're renowned for their plain chocolate, made from the finest dark couverture, and can claim the Queen as a fan. charbonnel.co.uk