Freeze your nuts – but not your mushrooms! 28 thrifty, fabulous ways to use your freezer

Almost all of us have a freezer of some size, and yet so few of us maximise its potential. If you’re like me, it’s sat there filled with nothing more than a bag of peas, a half full sack of oven chips, a tray of ice cubes and some pre-pandemic fish fingers. But it’s always on, always consuming energy.

It doesn’t have to be like this – your freezer is an amazing kitchen tool; the long-stay car park of your fridge. Because the freezer has been around for so long, we forget how versatile it can be. “If the freezer had never been developed and it came out like the air fryer did, people would be like, ‘God, this is amazing!’” says Suzanne Mulholland, the bestselling author and batch-cooking expert better known as The Batch Lady.

Mulholland, whose latest book The Batch Lady Rapid Dinners is published on 13 February, likens her freezer to the advent of streaming. “Years ago you would have to wait for the adverts, and then you’d go running out to make a cup of tea,” she says. “Now we watch whatever programmes we want, we pause it, and we come back to it whenever we want. And that is what your freezer is allowing you to do. It’s allowing you that control where you don’t have to cook from scratch when you need to feed everybody, or when you’re hungry. You can cook when you want to cook, at a time that suits you.”

Here, then, are 28 ways to get the most – and the best – from your humble freezer.

1. Don’t worry too much about keeping your freezer completely full. The question of whether a full freezer runs more efficiently than an emptier one is endlessly debated, and largely misses the point: it’s barely worth your consideration. One US freezer manufacturer reckons that keeping your freezer completely full, as opposed to completely empty, would amount to savings of a couple of dollars a year. One thing is certain: an empty freezer consumes energy to no purpose, so put yours to use.

2. Home freezing should be about making life easier. Mulholland deploys her freezer to spend less time in the kitchen, not more. “My background is that I’m a time-management specialist,” she says. “When I got married, had kids and left my lovely job in London, I suddenly thought, ‘This is ridiculous. There must be a much more efficient way to do this, rather than cooking from scratch every night.’”

3. Cook double, freeze half. That’s the basic formula for successful batch cooking, according to Mulholland. “It’s very efficient, because you can double a recipe in about five minutes,” she says. “So five minutes extra to make a whole other night’s meal, and you’ve done the same amount of washing up and the same clearing up.”

4. Start small. You don’t have to go all-in with a month-long meal plan. “I tell people, do it one night a week,” says Mulholland. “Just double whatever you’re doing that night and put it in the freezer. Because, I tell you, it becomes addictive.”

5. Freeze your nuts. “Nuts and seeds go rancid very quickly, because they’re full of oil,” says food writer Jane Lovett, author of The Get-Ahead Christmas Cook and Deliciously Simple. “Keep them in the freezer and they’ll be fine for ever more.” This applies to walnuts, sesame seeds, pumpkin seeds, sunflower seeds, almonds, pecans and pine nuts. “You don’t need to thaw them out – you can use them straight away,” she says.

6. Bear in mind that some things don’t freeze well. “Anything with a high water content will generally come out very soggy,” says Mulholland, “like lettuce or fresh tomatoes, as an example. There’s too much water in them, so when they freeze they crystallise, and then they just sort of go into mush when they come out.” However, if your fruit is going into a compote anyway, then mush is fine.

7. Never freeze mushrooms. They will go slimy.

8. Get to grips with “open freezing”. In the simplest terms, open freezing is the home cook’s approximation of industrial flash-freezing. Spread whatever you’ve got – berries, chopped veg, individual biscuits, etc – on a tray in a single layer and freeze. That way it freezes faster and doesn’t stick together in clumps. Once everything’s rock hard you can transfer it to a freezer bag or tub, so you can thaw and use as much as you need.

9. Freeze safely. According to the Food Standards Agency, chilled perishables can still be frozen until midnight of the “use by” date on the label, but home-cooked foods should be frozen as soon as possible (but not before they have cooled completely). Meat is generally best eaten within two or three months; fruit and veg will keep well for three or four months.

10. Before you freeze something, get rid of any air. Food surfaces left exposed to cold air will dry out and be subject to freezer burn – it won’t affect safety, but it will affect taste. If there’s a big air gap in your half-full plastic tub of leftover sauce, use a smaller tub.

11. Get some freezer bags. They’re inexpensive, sealable, reusable and compact. “We use freezer bags for everything these days,” says Mulholland. “It’s the modern way to batch cook. We freeze everything flat, so it literally looks like books.” Flat bags save space, stay airtight and defrost much quicker. You can even buy compostable ones.

12. Invest in a freezer-bag stand. “If you think about it, you’ve got a bag, you’ve got a pot, you’ve got a ladle, and you sort of need another set of hands,” Mulholland says. She uses a handy little two-pronged clip stand that holds your freezer bag open and upright. “They’re a phenomenally good gadget to have.”

13. Defrost safely. According to the Food Standards Agency, frozen food – and meat in particular – should only be thawed in the fridge. Freezing doesn’t kill bacteria: it only pauses its growth. The more time meat spends in the “danger zone” between 8C and 63C, when bacteria can multiply rapidly, the greater the risk.

14. Better still, learn to cook from frozen. “In my books, I always give a huge list at the beginning,” says Mulholland. “If you never want to defrost a meal and you always forget, here’s a list of everything in this book that will cook from frozen.”

15. If in doubt, follow a freezer recipe. According to Mulholland, getting the best from your freezer means using a recipe intended for it. “If you put leftovers into a freezer, they’re not miraculously going to become an amazing meal,” she says. “The recipes that I write are freezer recipes. They are made for the freezer. They’re cooked in a different way.” Many of Mulholland’s recipes involve freezing the raw ingredients of a meal together – meat, veg, spices, everything – so they can be defrosted and dumped into a slow cooker.

16. Roast potatoes can also be cooked from frozen. According to Lovett, frozen roast potatoes actually need less time in the oven. “I’m no scientist,” she says, “but I think the reason they cook quicker is because they’ve dried out a bit in the freezer, so they don’t have so much moisture.” To prepare the potatoes for freezing, peel them, cut them into evenly sized chunks and parboil for 15 minutes. Open-freeze them on a tray and when they’re hard, slip the potatoes into a freezer bag.

17. Label everything clearly. This is a lot more important than it sounds: whenever you freeze something, write down what it is – and the date it went into the freezer – on the bag or container in indelible ink. “I always think I’m going to remember,” says Lovett. “I really don’t.” UFOs (Unidentified Frozen Objects) rarely escape the freezer, because nobody ever wants to take the risk.

18. If you run out of bags, don’t worry. Line a bowl with cling film, fill with soup, sauce or whatever, and freeze. As soon as it’s solid you can remove the bowl-shaped chunk of soup, wrap it up tight in the cling film and store in your freezer.

19. Stock up on pre-chopped frozen veg. Bags of frozen pre-chopped and pre-sliced vegetables can save you a lot of time and effort, and if you’re using it in stews, casseroles or curries, you will notice little difference. “I’m a massive fan of already frozen chopped onions,” says Mulholland. “You buy them from the freezer aisle. You can also get already chopped herbs, things like ginger, garlic, chillies.”

20. Save money. Prepared frozen veg is often cheaper than fresh (and often technically fresher, since it was frozen shortly after picking). Frozen broccoli florets, for example, cost about £1.19/kg, while fresh broccoli currently sells for around £2.19/kg, and fresh broccoli trimmed into florets can command as much as £9/kg.

21. You can even buy a preprepared soffritto mix of finely diced carrot, celery and onion (sometimes sold as “veg base mix”) as the foundation for countless soups and sauces.

22. Freeze breadcrumbs. Producing fresh breadcrumbs requires the purchase of a whole loaf of bread you might otherwise not need. Whiz the whole loaf into crumbs, and then freeze what you don’t use. “They don’t set hard,” says Lovett, “so you can take out as many as you like.”

23. Freezing bread also isn’t just convenient – it’s better for you. It has been shown that freezing bread turns some of its carbohydrates into resistant starch, which resists digestion and lowers your glycemic response (the rise in blood glucose after eating). Toasting bread does this as well; freezing and then toasting bread does it more.

24. Freeze grated parmesan. “It’s a labour of love, grating two ounces of parmesan,” says Jane Lovett. “So I buy a great wedge of parmesan, more than I’m going to need.” She grates the cheese in large quantities using a food processor. “You can use it straight from the freezer.”

25. Freeze gravy. “If I’ve got leftover gravy,” says Lovett, “I just freeze it in a little tub or in a yoghurt pot, and I label it lamb, beef, pork, whatever it is. Then the next time I’m making that sort of gravy, I will add it, from frozen, to the gravy I’m making, which makes it even nicer.”

26. Freeze fresh herbs. You can preserve the flavour – if not the structure – of chopped fresh herbs by freezing them in ice-cube trays topped up with water, or in freezer bags with a coating of some neutral oil. Alternatively, you can buy most herbs – including thyme, parsley, coriander and rosemary – already chopped and frozen from the supermarket.

27. Freeze your egg whites. Like me, you probably use more yolks than whites over the course of a year. Also like me, you may well end up throwing your egg-white surplus away. But you can freeze them instead. After thawing, an egg white can still be whipped into stiff peaks. “The older an egg white is, the better it whips up,” says Lovett. One egg white, she says, is roughly equivalent to 30ml or one fluid ounce, allowing you to separate them into appropriate portions before freezing.

28. Don’t buy ready meals when you can make your own. “I don’t want to go and buy a ready-made curry when I know that I can make a homemade curry in 10 minutes and it’s super healthy,” says Mulholland. “It’s a much nicer way to live. You’re managing to fulfil that lovely dream, which is eating really good, nutritious, home-cooked food, but you’re not slaving over a stove. I don’t like cooking – my publishers go nuts that I keep telling people that, but it’s true.”

• Suzanne Mulholland’s new book, The Batch Lady Rapid Dinners, is published by Ebury on 13 February. To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.