Members of the public aren’t usually allowed inside Rebecca Knights-Kerswell’s chocolate kitchen, although they occasionally press their noses up against the windows to watch her at work. Everyone is interested in the process of making chocolate, which is why Rebecca - who makes all the chocolate for her Edinburgh shop Coco of Bruntsfield - has decided to run a chocolate school for two or three pupils, twice a month. I’m one of the first.

The chocolate kitchen is a tiny room full of pink sunlight, with two marble tabletops and a trapdoor to the basement. It’s when you lift the trapdoor that the smell hits you, because downstairs is where Rebecca keeps her chocolate tempering machine - something between a chocolate fountain and one of Willy Wonka’s creations, which maintains glossy molten chocolate at fixed temperatures, and leaves a smell in the air that’s like honey but deeper.

Chocolate tempering is an exact science, we discover. The raw chocolate - huge bowls of what look like large dusty chocolate buttons - needs to be melted down and maintained at very precise temperatures until a molecular change occurs in the crystallisation process, creating sheen and perfect texture. Downstairs, the machine keeps Rebecca’s dark chocolate at precisely 32°C, but we’re going to be hand-tempering the milk and white, which needs to be worked with at 29°C and 28°C respectively. We use microwaves, heat guns and laser thermometers to raise and measure the temperature, but the actual process of tempering is surprisingly low tech. Take one enormous bowl of melted chocolate and tip it all over a smooth marble tabletop, then maintain motion with a palette knife and scraper until the chocolate reaches consistency.

‘Go on, just pour it!’ Rebecca says, encouragingly. This feels very wrong - it’s a table, and some wee Presbyterian gremlin is hissing that I ‘shouldnae play with my food’ - but the best part of this process, I’m finding, is transgressing that particular boundary.

Rebecca is one of a very few chocolatiers in the country who still tempers by hand. ‘Other chocolatiers like to avoid the element of risk,’ she says, serenely. The risk, we deduce, makes it all the more fun.

We start off with milk chocolate scattered through with mixed fruit, chunky star-shaped moulds filled with raspberries and white chocolate. Then it’s time to move on to the grown-up stuff, and I’m ashamed to admit that I’ve never really taken to dark chocolate before. I’ve never infused my own dark chocolate with cardamom either, though.

There is lunch at a local restaurant to fuel us before the hard work starts in earnest - the sticky, finicky business of filling dark chocolate hearts with a fondant made from pure rose oil (and getting a mouthful of flowers for our efforts), and the sheer physical labour of hand-shaving thin-set chocolate off the marble to make real hot chocolate. At the end of the day, we package up our products to take home (Rebecca cheerfully ordering us to eat anything that isn’t quite good enough) and emerge, beaming and content, with an estimated £50 worth of chocolate each. ‘I made it myself,’ I insist on telling everyone in the office proudly; still with the smell in my hair.

For more information on Coco’s chocolate school, visit www.cocochocolate.co.uk