"I get letters still, sad letters, saying, 'I'm a pensioner, your book has really helped me. My wife is really sick and I don't know what groceries to buy'," she said. "This is an extension of that, and over time I've been refining these systems to make people's lives easier while also saving a hell of a lot of money."
The full grocery list, from tinned tomatoes and chicken noodles to beef mince and tortilla wraps, comes out to $168 - the prices are accurate as at March 23, 2017 - or A$42 per week, with each $6 meal feeding four people.
"I spent six weeks just shaving off costs," she said. "I've tried online shopping with Coles and Woolies, Aldi, the local greengrocer. Aldi won - this system is the most cost-effective."
With meals like pesto pasta, pea and ham soup, chicken pie and chili con carne, it's eating on a budget, but "we call it budget gourmet", she said, adding her 11- and six-year-old kids "loved every meal I've cooked".
"On the other side of the coin, there are a lot of mums who are trying to lose weight and are pretty stressed out," she said. "They struggle to balance the family budget, and those meals are not in line with their health goals.
"At A$42 a week you're not going to be eating steak, but my style is to have a budget meal but to jazz it up on the night. For example, you might be having a chicken stir-fry but add some shredded lettuce."
After the mammoth shop, be prepared to spend a lot of time in the kitchen.
"You spend a whole Saturday, and you pretty much cook five bulk meals for the month," she said. "It's 28 meals in total, but eight of those are fresh you cook on the night. What it does is take away the weeknight stress, and also the takeaway nights."
Ms Petersen, whose frugal living habits helped her family go from A$50,000 in debt to owning their own home, admits it's "not for everyone". "People that love their steak, they're not going to be interested," she said.
But if you're on a low income or pension, saving to a very strict budget, or just want to learn to control your grocery bill, "planning is better than not planning".
"We've been doing it for three months now," she said. "If I don't plan and don't have a system, it's A$200 a week for our family - I'll just go to the shops and randomly buy stuff. At a minimum [we're saving] A$100 a week, over three months that's A$1200. That's like an airfare for someone."
Ms Petersen argues it's crucial to rein in that kind of impulse purchasing.
"It's so easy to go in and buy random stuff, and because of that lack of planning, people's grocery bills are often in the A$200 a week mark," she said. "The strength of the marketing is often the reason people don't meet their budgets, so this is really a guide.
"Once you've used the system once, it actually trains you to put your blinkers on, rein in spending, stick to a list and be conscious of how easy it is to overspend."
