UK firm Biscuiteers is giving cookies a makeover - from advent calendars to doll's houses

Most people don't find themselves getting overly excited about biscuits. The office rush on a packet of custard creams at tea o'clock is about as sought after as they get.

But on a weekend trip to New York in 2007, Harriet Hastings decided that, as with cupcakes, doughnuts and macarons, cookies were due a fashionable makeover. It was then that the marketing executive's "boutique" biscuit company was born. I meet her, along with her husband and co-founder Stevie, at the Biscuiteers factory, which is sandwiched between a Kurdish cultural centre and a car mechanics in Kennington, south London.

"I noticed that giving food and wine as a gift is something that people do a lot, but there weren't many interesting ways to do it," she tells me as we sit in her office, which is filled with framed biscuit butterflies. "Stevie runs his own catering company so creating an e-commerce business in food was the obvious choice. It needed to be something that we could post that had a long shelf-life, so hand-iced biscuits that came in beautiful packaging had potential."

Biscuiteers launched in September 2007 using Stevie's kitchens, but by November they were so inundated with orders that they had to find new premises. "That first Christmas was chaos," says Harriet. "I was pulling in friends to come and help, it was that hairy. But we got through it and then we were off."

Below us, a team of around 30 icers in hair nets and white coats, most of whom are artists on the side, are assembling gingerbread houses and piping coloured paste onto biscuits shaped like thermometers and plasters for the First Aid Tin – one of the company's best sellers. At the moment, staff are packing 2,000 biscuits a day to ship worldwide, completing orders for biscuit advent calendars (yes, they're a thing) and icing logos onto "biscuit cards" for corporate Christmas parties. They've made edible versions of Jeff Koons' lobster for the launch of his exhibition at The Serpentine and a William and Kate "collection" to celebrate the Royal Wedding.

If you can think of it, chances are Biscuiteers has iced it. Last year, the team spent 400 hours creating Lost London, a skyline featuring demolished or never-built buildings, entirely out of biscuit, for the Selfridges Christmas window and assembled a life-size gingerbread house for Charlotte Olympia's Paris fashion show. "I love anything that stretches the realms of possibility," says Harriet, sounding like a biscuit-based Willy Wonka. "The girl who works with us at the moment is a trained architect because the same building principles apply even if you're using gingerbread. We're doing a huge project for Leeds Castle where we've recreated the castle as a doll's house entirely made from fondant and biscuit."

Even on a small scale, the biscuits are so detailed that they are almost works of art, which perhaps explains why a tin of 16 costs around £40. But for anyone with a steady hand and a tight budget, the Biscuiteers Book of Iced Biscuits shows how to make them at home. "Anyone who tries it will realise that icing to that quality, by hand, is an incredibly time-consuming process," says Harriet. "When we started, our mission statement was, 'Why send flowers when you can send biscuits instead?' and if you think about the price points of flowers, they're not dissimilar.

"Everything is done by hand and I don't think customers would buy them if they felt that they were being knocked out by a robot," says Stevie. He started his catering company, Lettice, on the back of a bike. "I put some barbecues on my bicycle and went to some pubs to sell satay, which is a thing in Singapore. I managed to set fire to myself on Fulham Broadway." After a few more flammable setbacks ("Remember when you lit barbecues in someone's office?" interjects Harriet), he now creates food installations for events in the art world.

In 2012, Biscuiteers opened its first shop in Notting Hill, London, which has the UK's only icing café. "People think it's all about kids, but it's just as likely to be two young professionals coming in after work for icing lessons," says Harriet. "David and Harper Beckham are regulars and we made the biscuits for her birthday party. David Cameron came in the other day with his daughter and bought some cookie cutters."

This week, she and Stevie open a second branch in Clapham, with an open icing kitchen and a larger café to sample biscuits alongside a new range of hand-iced chocolates and cupcakes. "We'd like to open more shops and take the concept of an icing café international," says Harriet.

A branch on every high street? That would be the icing on the biscuit.