Byline: Andrew Billen

On the way to Times Towers the celebrity cook ate a Sainsbury's mini doughnut. Worse, she enjoyed it. This is not, however, a scandal of the magnitude, say, of a junk-food scourge such as Jamie Oliver ingesting a Big Mac. Ruby Tandoh's Twitter profile leads with the boast "i f***in love doughnuts" and the first chapter of The Great British Bake Off runner-up's new book, Eat Up!, invites us to imagine a Krispy Kreme in our hands, "the sticky edges where doughnut meets skin". Celebrate, oh celebrate, the doughnut.

"I just wanted to set the tone early and make it clear that this wasn't a foodie book. It wasn't going to be 'Here are the best markets to get your aubergines from,' " Tandoh says over a cup of tea in a bar around the corner.

And today's doughnut? "I didn't plan to have one for breakfast. I wouldn't endorse it as a breakfast, but this is what I want from the book. I had the doughnut in my bag and I was hungry. If I had stopped for breakfast I would have been late and if I didn't have breakfast I'd have been starving. You have what's there because it's so much better to eat something, especially if it's as delicious as a doughnut, than to be terrified of eating it."

Tandoh, 25, does not identify as a celebrity chef. Despite being eminently telegenic and articulate, she hates being on TV. Nor was she offered a series after Bake Off in 2013, probably, she thinks, because producers feared she might "flap", given that she had a teary meltdown in the contest's semifinal. Then again, she was only a 21-year-old philosophy student and in the midst of what the book reveals to have been a six-year-long eating disorder.

She is instead a food writer and a cook, until last month working as a pastry chef in an arts cinema cafe in Sheffield, the city to which she has moved with her girlfriend. The shifts kept getting longer, so she resigned on winter solstice, but wants to get another restaurant job soon.

I cannot judge her cooking, but her writing in Eat Up! is moreish. Her third book is witty, thoughtful, epigrammatic, sometimes scholarly and always passionate. Some passages head for Pseuds Corner. We are, she writes, "myth, intestine, splendour, fart, divinity and heaviness all at once". A well-stocked supermarket aisle is "a cubist masterpiece". There is a "recipe" for how to drink a can of Fanta. Yet these excesses of exuberance are more than made up for by apothegms such as "Plant your feet firm in your principles, but let your body sway in the breeze." She abandoned her degree...