A year ago, a bright, unemployed 24-year old single mother in Southend summarised in a blogpost the fear, humiliation and desperation of living on the breadline. It is one of the most moving and vivid accounts of the reality of modern poverty.

The piece, entitled Hunger Hurts, was written when Jack Monroe was at her wits' end: no money, the food cupboard bare, the housing benefit cheque turning up, inexplicably, £100 short. Monroe describes in intricate detail how she had asset-stripped her life to pay the bills: sold her watch, iPhone and TV. She writes of the energy-sapping boredom of "getting by", and the paradox that the poorer she gets, the more expensive her electricity becomes as the supply is moved from mains to meter.

"Poverty is the sinking feeling when your small boy finishes his one Weetabix and says: 'More, Mummy, bread and jam please, Mummy,' as you're wondering whether to take the TV or the guitar to the pawnshop first, and how to tell him that there is no bread or jam," she wrote.

This and other posts are filled with the minutiae of a life in poverty: the forensic, penny-pinching accounting that accompanied every trip to the supermarket; the shame of referral to a food bank; the time she sold the entire contents of her house – crockery, curtains and all – to pay off rent arrears; the hundreds of failed job applications, painstakingly typed out on a mobile phone; the dread that all this paupery might somehow attract the attention of children's social services.

Austerity recipes

It wasn't just the accounts of poverty that set the blog A Girl Called Jack apart, however, but the recipes. Scores of them, beautifully set out and photographed, and carefully costed: Mumma Jack's Best Ever Chilli, 30p ("Since Sainsbury's has hiked up the price of kidney beans, I've bought dried ones"), or Oh My God Dinner, 28p.

Filled with humour and almost real-time practical advice about the weekly price movements of supermarket food, it is a plain-speaking, practical austerity cookery guide – quite literally how to feed yourself and your toddler on £10 a week, in ways that are healthy, tasty and, importantly (to relieve the tedium of baked beans), varied.

The recipes require the bare minimum of kitchen equipment ("If you just have an electric two-ring plug-in you can cook most of the things that I cook"). They are fuel-efficient, rarely taking longer than 15 minutes to prepare. Ingredients are what you might find in an ordinary local supermarket. There is a risk, of course, that Monroe's recipes will be seized upon by people eager to "prove" that food poverty is a myth, or that benefit payments must be too high. Cooking can be done cheaply, she says, but it is more complicated than that. She had been passionate about cooking ever since her food technology course at school ("a form of escapism from all the words and numbers"). Not only did she have the skills to experiment with her own dishes, she says, but, more importantly, she had the confidence.

"Food poverty comes in two strands. The first is not having enough money to buy food for yourself and your family. The second is poverty of education. If you give someone £20 and say, 'Feed your family for the week on it,' a lot of people just couldn't do it adequately and that's because there's – and I do blame the readymeal industry for it, because it is so easy and so attractively packaged, and you just put it in a microwave – a disconnection between what's in that packet, and how simple and cheap it might be to make it for yourself. I think if we can solve food education then we are part of the way to solving food poverty."

If anything, her blog is a colourful rebuke to the commenters who sneer that people on benefits should just make a cheap lentil stew to last them all week: "I do use lentils in my cooking – I make polenta bolognaise, I make burgers out of them – but I do get infuriated by people who say, 'Oh, just eat lentils.' Actually if you were to buy a bag of dried lentils it would cost you a couple of quid. Some people don't have that to spend in the first place. And not everyone wants to eat lentils."

She talks about how difficult it is for people who are already on low incomes to cope with further cuts to their budgets. Losing £14 a week to the bedroom tax may not seem a lot to some people, but for others, she says, it will mean they go hungry. "There are people who can't save £4 a week [let alone £14]. There are people like me who when Sainsbury's put the price of a basics jar of jam up from 29p to 35p it means you have got to put something back in your shopping trolley because that 6p price rise has priced it out of your shopping basket.

"I think back to this time last year. When you've got to the point where you have unplugged your fridge and you have unscrewed your light bulbs and you have sold everything you own and you are eating value kidney beans out of the pan, or using the child's formula milk that the food bank gave you. Where was I supposed to find £14 back then?"

Things have picked up for Monroe since last July. The blog is a huge success. Penguin signed her up to write an austerity cookbook (due out in February 2014). She makes the odd TV appearance, talking about poverty and benefits. In February, her local paper, the Southend Echo, gave her a job as a trainee reporter. In May, her blog won the judges' choice prize at the glitzy Fortnum and Mason food awards (they praised Monroe's recipes as "so nutritious and thrifty that they are being handed out by food banks as examples of how to manage on next to nothing"). As I finish my interview with Monroe, Sheila Dillon of the BBC Food Programme turns up to interview her for a programme on austerity food.

Not bad for the working-class girl who won a place at a posh grammar school, but left at 16, bullied and disillusioned. Monroe might still be a well-paid call handler for Essex fire service had she not resigned because she could no longer juggle night shifts and motherhood. The blog might not have happened had she not been unemployed for 18 months, and been turned down for hundreds of jobs, many of them because she was considered "too old" at the age of 24. Poverty, almost paradoxically, gave her a voice.

Not that she is in the clear, financially. When the BBC reported that she would be paid £25,000 for her book deal, the housing benefit office suspended payments until it saw her book contract, nearly causing her to be evicted. She has moved to a cheaper house share to escape the tyranny of housing benefit. "Because I'm in the media quite a lot now, everyone assumes that everything is fine. People forget I sleep on a mattress on the floor with my son in a house I share with five other people. They see me on Sky news and think, 'Oh, you must be loaded.'" Yet she is now one of the working poor: "I go out to work every day, but I still can't afford to make ends meet."

She is an energetic anti-poverty campaigner, infuriated by the media's vicious attacks on "benefit scroungers" and the inability of politicians and policymakers to comprehend the slender margins of breadline life. "I'm not going to stop championing causes, campaigning and stamping my feet about things that are wrong, just because I may not be in that position any more. Until people realise benefits doesn't mean scrounger, and austerity isn't a fun middle-class way to grow your own vegetables, there's still a lot of work to do."