If you don’t own a Ninja air fryer, I’ll bet you know someone who does. The clever kitchen gadgets have built up quite the following, and for good reason.
The brand’s most well-known model is the family-sized foodi, which proved so popular at launch that it was sold out for months, quickly acquiring ‘must-have’ status. It was a similar story with Ninja’s double stack air fryer, which launched last year to a huge number of pre-orders. The demand was partly due to the brand’s reputation and partly to this model’s innovative new design.
The double stack flips the idea of a traditional dual air fryer (with a duo of cooking baskets side by side) on its head, stacking the two baskets one on top of the other. The idea is that this takes up much less space on your kitchen counter without sacrificing quantity.
Adding an extra shelf in each basket takes things up a level, but does all of this actually equate to a better cooking experience? Fresh from writing a guide to the best dual air fryers, I took a deep dive into the Ninja double stack’s features to see if this model really lives up to the hype.
How I tested
I set up the Ninja double stack in my kitchen, where the appliance became the go-to family air fryer for three weeks. I tested all the features – from baking brownies to air-frying chips and even dehydrating fruit – and took notes on each setting and how easy it was to program. I also paid close attention to ease of setup and cleaning, to really get the measure of this machine. Read on for my full review and verdict.
Why you can trust IndyBest reviews
Katie Gregory has been writing consumer reviews for The Independent since 2021, covering everything from the best ice cream makers to top toaster and kettle sets. Katie recently put a whole collection of air fryers through their paces for her guide to the best dual air fryers, so it’s safe to say she knows what’s what when it comes to air frying. In all her reviews, Katie provides her honest opinions and will only recommend products she believes are worth your money.
Ninja double stack two-drawer air fryer, SL300UK
Setup
This kitchen appliance made a good first impression as it arrived fully assembled. All I had to do was remove the packaging and wash the air fryer’s removable parts in hot, soapy water, and then the device was ready to go.
The double stack air fryer comes with an instruction booklet, a full-colour quick-start guide, and a one-page reminder of how to use the layered cooking method (more on that later) with suggested ingredients.
The instruction booklet contains details on safety and troubleshooting, and the quick-start guide includes lots of colourful recipes, but beyond that, both booklets contain a lot of duplicated information about how to cook with the machine, so I mostly used the quick-start guide.
Design
Most dual air fryers have two side-by-side cooking baskets, with control buttons above them. However, as the name suggests, this model stacks the baskets one on top of the other. Each basket contains a removable, non-stick crisper plate, which sits on the bottom of the basket at a choice of two heights.
Each basket also contains a removable, raised metal rack with handles, which adds a second cooking surface. Crucially, that means, across the two drawers, you can cook food on four layers, rather than two, bringing the overall capacity to a very reasonable 7.6l, despite the machine’s compact size.
Each basket measures 19cm x 19cm, not including the handle. Factor in the housing and the control panel, and at 28cm wide and 38.5cm high, this machine is about 25 per cent slimmer than standard air fryers while also fitting under kitchen cabinets, which I found really makes a difference on the countertop, particularly if you’re tight on space. It’s not exactly tiny, so you’ll have to make some room for it, but it’s relatively sleek. Not only is the double stack slimmer than other two-drawer air fryers, it’s slimmer than some single-drawer air fryers, so it’s no gimmick – you really are saving on space.
Controls
The Ninja double stack’s controls are on the side of the machine, not on the top like most air fryers, making them easy to access. However, I was less keen on the loud beeping every time you start or end the cooking process. It would be nice to have the option to switch off this feature.
The two baskets can be operated independently, too – you can set each one to a different temperature, cook using just one basket, or use both at the same time. With some air fryer models, opening one drawer also stops the cooking process in the other drawer – an annoying feature that, thankfully, the Ninja double stack doesn’t have.
The exception is when using the match function, which copies your cooking settings across both baskets. This means if you’re cooking the same thing in both drawers, you can set one to the desired temperature and time, press the match button, and then all the settings are reflected in the other drawer.
I also got a lot of use out of the sync function, which lets you cook two different things at different temperatures and durations, but syncs the baskets so everything is ready at the same time. For this one, you just need to program each drawer, press sync, and then start. The basket that has the shorter cooking time will then be on hold until it’s time for it to kick into action.
Air frying
The heating elements are at the back of the machine, and the baskets have a ventilated back panel to enable heat and air to circulate around the food. I found this works well when using the stacked shelves to air fry, but it meant that I needed to use liners when cooking ‘wet’ food – when baking brownies, for example.
When air frying, I found there was a bit of a knack to getting the best results from the double stack. For example, my first batch of chips (an air fryer staple in my house) was abysmal, mostly because I hadn’t paid attention to the instructions.
It’s pretty standard to need to shake the contents of the baskets during cooking with most air fryers, and many have a shake reminder at intervals during the cooking process. Unfortunately, the double stack doesn’t, although the booklet states very clearly (and very often) that the contents need to be shaken at least three times during cooking.
Realistically, with chips, I found you need to shake every five minutes for even results, otherwise they cook far more quickly at one end of the basket than the other. Once I’d resigned myself to the fact I’d need to stay on standby for regular shaking duties, I was able to cook chips evenly and quickly, but it does take some getting used to.
There is, in fact, a whole section on cooking chips in the instructions, including soaking homemade, non-frozen chips in water for 30 minutes before cooking. You should also pay attention to the note about the positioning of the crisper plate, depending on what you’re cooking, as it really makes a difference to airflow and cooking quality.
Cooking stacked meals
When cooking a stacked meal using the metal rack, Ninja recommends that proteins are cooked on the top layer and vegetables and starches are cooked on the bottom, as the top layer crisps up quicker.
I tested it with chicken breasts on top and new potatoes on the bottom, for 20 minutes, as the booklet recommended, and found the chicken was cooked in 15 minutes, whereas the potatoes needed 10 more minutes to fully crisp up.
In fairness, I was quite generous with the potato portions and found that chopping them as small and as evenly as possible made a big difference. The juices and spices from the chicken on top flavoured the potatoes on the bottom, which was a bonus.
I also tested the stacked method with vegetables on the bottom and found these cooked at the same speed as the chicken. It’s also worth noting that, while the packaging promises meals for six people, I found four was more realistic.
Extra functions
While I mostly used the air fry function, I also tested the max crisp, roast, bake, dehydrate and reheat settings, and was pleasantly surprised by the results.
I’d usually make roasted crispy chickpeas in the oven in about 20 minutes plus pre-heating, for example, but crisped them up using this air fryer’s roast function in just eight minutes. Likewise, I found that I could use max crisp – recommended for frozen items – to cook frozen halloumi fries in record time.
My kids and I also tested the bake function, using the peanut butter brownies recipe in the back of the Ninja booklet. We were delighted to tuck into a batch of deliciously spongy, fudgy brownies after minimal effort.
The one function I didn’t particularly rate was the dehydrate option, which I tested by making dehydrated strawberries to add to breakfast cereal. The setting automatically selected six hours, which seemed like a very long time to shrink about eight strawberries, and they needed another two hours on top of that to fully dehydrate. It’s not a function I would ever use again.
Cleaning
While the baskets, racks and crisper plates are dishwasher-safe, Ninja recommends hand-washing these parts. I tried both options, and the baskets and crisper plates were easy to clean by hand, even after weeks of cooking.
Plus, the baskets fit in a standard washing-up bowl as well as a dishwasher – not something that can be said for bulkier air fryers. The racks, which aren’t non-stick like the other parts, take a little more scrubbing, so I mostly opted to pop them in the dishwasher.
Buy now £182.99, Ninjakitchen.co.uk
The verdict: Ninja double stack air fryer
The fact that the Ninja double stack takes up less space than a traditional dual air fryer is a big plus point – I’d say it’s the primary reason for choosing this model over others. Despite the clever stacked cooking design really maximising the internal space, the baskets are still relatively small, though, so I’d recommend it for a family of four or possibly five, but not six.
The functions work well, but bear in mind that chips seem to require more shaking to cook evenly compared to other models. As long as you’re happy to get a bit more involved in the cooking process – with shaking, tweaking and fine-tuning being essential to good results – this is a strong, space-saving option for smaller kitchens.
Want more recommendations? Check out IndyBest’s guide to the best air fryers
