Bakery owner Bea Vo, of Bea's of Bloomsbury, who runs four cafes across London, was shocked to discover that "her" invention, the duffin, a cross between a doughnut and a muffin (what was wrong with "muffnut"?), has been trademarked by Starbucks supplier Rich's Products. Supposedly irritating though this may be for the parties involved, it has been a stroke of PR genius for both Bea's and Starbucks, which has never had enjoyed so much fanfare about a new menu item. Google the word "duffin", which was not on anyone's radar a week ago, and you get 2.6m results.
Starbucks says it has no intention of preventing Bea's from making duffins. Which is a good job, because anyone who owns Nigella Lawson's How To Be a Domestic Goddess may have been rolling them in melted butter and granulated sugar at home ever since the book came out in 2000. They're in the section on children's baking. She calls them "jam doughnut muffins".
The duffin row, apart from inspiring such brilliant headlines as "Baking Bad", is a mark of the way baked goods have become big business. Demand for freshly baked bread products in the UK has risen by 20% since 2011, according to international bakery group Lantmannen Unibake. Artisan bakers are also seeing an upsurge in demand for "gourmet bread": sourdough at £4 a loaf and others such as Borodinsky (made with Russian rye).
But it's as much of a DIY thing as a retail trend. When David Cameron struggled recently to guesstimate the price of a loaf of bread - "Well north of a pound?" - he said it was because he likes to bake his own. And as the semi-finals of the Great British Bake Off draw near - now, improbably, in its fourth series and pulling audiences upwards of eight million - the whole nation has gone baking mad. Anything the show touches turns to gold. Even the outfits worn by judge Mary Berry see a sales spike after featuring on the show: a floral bomber jacket by Zara flew out of stores. Berry's autobiography, Recipe for Life, published last month, is already riding high in the bestseller charts.
Just as Delia Smith once quadrupled cranberry sales in 24 hours, the Bake Off effect is well-documented. Last year sales of cake stands at Marks and Spencer rose by 243% in the runup to the series finale. Even flour sales surged (wholemeal up 69%; plain up 20%; self-raising up 10%). John Lewis sold 70% more breadmakers, and baking product sales increased by 67%.
The Women's Institute reports signing up more than 50,000 new members during the first two series. "The show has captured the imagination of the nation and this is reflected in people signing up," it said.
"I think it's a reaction against the mundaneness of so many ready-made baked things," says master baker Dan Lepard, a judge on the Great Australian Bake Off(yes, this brand is now global) and author of Short & Sweet: The Best of Home Baking (Fourth Estate, £25). "We'd all love to open a box of cakes from the supermarket and find that they're extraordinary, but the reality is that they rarely are. Home baking is giving people the results they'd hoped for, and a buzz from knowing they've done it themselves. I know this because people send me their proud pics daily."
In the previous few hours people had tweeted him pictures of oat and sour cherry cookies, chocolate pecan cake and black millionaire's shortbread.
Keen home baker, mother of two daughters and Bake Off superfan Rachel Krys sees the popularity of the show as "a sort of austerity response": "It just feels so frugal to use some leftover butter and a bit of drying fruit to create something delicious. And it's more of a collective activity. I learnt to bake with my nana and my mum. It was something they liked to do. This is probably why I bake with my children: it entertains them while being something I actually need to do."
It feels like there is a tension, though, between rediscovering the innocent pleasures of home baking and pushing the limits of frenzied, trend-hungry consumerism. Duffingate is the economic side of foodie fetishism. Bea Vo, a former head pastry chef at Michelin-starred restaurant Nobu in London, said: "They own the trademark. The only purpose of owning the trademark is to protect the name. But they're protecting something that they clearly aren't the originator of."
Vo has been selling "duffins" since 2011. "It's like saying we trademarked the word fairycake and we're going to let this one person make fairy cakes because they've come up with it. But everyone else, well, we're going to fuck them over." And the lowest blow is that the Starbucks product "isn't even a true doughnut-muffin," Vo sniffs. "It's a jam-filled muffin."
The duffin is a byproduct of the "cronut" (croissant-doughnut) craze that took off in May in New York when an experiment with rose Tahitian vanilla pastries at Dominique Ansel's bakery went viral. On the first day it made a batch of 50. On the third day it had sold out of 200 by 9.30am. One customer responded to news of this by sticking his finger up to staff. Then, although the $5 luxury cronut is said to be best consumed within six hours of purchase, a secondary market sprang up online at Craigslist, where they change hands for $25.
Since then bakeries have been rushing to invent their own mashups and trademark the name. The US press has already dubbed the trend "the overhyped hybrid pastry fad". The Starbucks consumerist seal of approval either represents the end of a foodie trend or the start of a whole new Franken-pastry era.
Among amateur bakers online, the craze has already spawned dozens of sickening/exciting (delete according to taste) "me too" creations: doughnut macaroons, ice-cream cupcakes, croissant pretzels, doughnut brownies and "pie cakes" (a pie with a sponge base).
Already many of the offerings on the Great British Bake Off are veering into this territory. Only in an obsessive foodie-focused culture could you present a prune and armagnac pudding with armagnac butterscotch sauce (Bake Off week seven) or a rose, almond and raspberry filo pie. The Great British Bake Off represents the Britain many people wish they lived in. But it's also supposedly a place where it's completely normal to keep cardamom, crystallised roses and harissa in your larder. Last week's "Signature Wheat-Free Bake" offering from Bake Off favourite Ruby Tandoh? Mango and nigella seed spelt cob.
My grandad, a grocer who got up at 6am six days a week for 30 years to take delivery of a lorryful of simple jam doughnuts, would have wept with shame.
Photo: The Great British Bake-Off is in its fourth series. Photograph: Des Willie/BBC/Love Productions