Gluten Free Flapjacks: Recipe and UK Buys
In this guide
Gluten free flapjacks are ordinary flapjacks made with oats that are labelled gluten free. Melt 150 g of butter with 75 g of soft brown sugar and 125 g of honey, stir in 300 g of gluten free oats, press into a 20 cm tin and bake at 170C (150C fan) for 22 to 25 minutes. Cut into 12 bars of about 240 kcal each.
Written by James Frost, founder of Flaming Phoenix and the maker of Phoenix Bars. Updated October 2026.
Gluten free flapjacks recipe (makes 12 bars)
Allow 10 minutes to mix, 22 to 25 minutes in the oven and an hour to cool in the tin.
Ingredients
- 300 g porridge oats labelled gluten free
- 150 g butter
- 75 g soft light brown sugar
- 125 g runny honey
- A pinch of salt (optional)
Method
- Heat the oven to 170C (150C fan, gas mark 3). Honey browns faster than syrup, so this is slightly cooler than most flapjack recipes. Line a 20 cm square tin with fresh baking paper.
- Melt the butter, sugar and honey in a large pan over a low heat until the sugar has dissolved. Do not let it boil.
- Off the heat, tip in the oats and salt and stir until no dry flakes are left.
- Spread the mixture into the tin and pack it down firmly with the back of a spoon, pushing it into the corners.
- Bake for 22 to 25 minutes, until golden at the edges and still pale in the centre.
- While it is still warm, mark out 12 bars with a knife, then let the slab cool completely in the tin before cutting along the lines.
Per bar (one twelfth of the tray): about 240 kcal, 30 g carbohydrate, 12 g fat and 3 g protein, calculated from typical UK pack values.
Swaps. Use 125 g of golden syrup instead of honey and bake at 180C (160C fan). For a dairy-free bar, replace the butter with a dairy-free baking block. For a fully plant-based version, use my vegan flapjacks recipe with gluten free oats.
Are flapjacks gluten free?
Most flapjacks are not gluten free. Oats do not contain the gluten found in wheat, barley and rye, but ordinary oats are usually grown, harvested and milled alongside those grains and pick up enough of them to matter. A flapjack is gluten free only when it is made with oats that are labelled gluten free and nothing else in the recipe adds gluten.
“Gluten free” is a legal term on UK food labels. It means the food contains no more than 20 parts per million of gluten. Phrases such as “pure oats”, “100% oats” or “organic” do not tell you anything about gluten, a point the UK's main gluten-free charity makes in its guidance on oats.
Can everyone who avoids gluten eat oats?
Not quite everyone. Oats contain avenin, a protein similar to gluten. The UK's main gluten-free charity says most people who avoid gluten for medical reasons can eat gluten free oats, but that a very small number are also sensitive to avenin. If you follow a gluten free diet on medical advice and are unsure about oats, check with your healthcare team before relying on any oat-based food, including the recipe and the bars on this page.
How do you make flapjacks without oats?
Swap the 300 g of oats for the same weight of buckwheat flakes, or a half and half mix of buckwheat and quinoa flakes. Despite the name, buckwheat is not wheat and is naturally gluten free, though the same rule applies: buy flakes labelled gluten free.
Flakes are finer and thirstier than oats, so two adjustments help. Bake for 3 to 5 minutes less, and press the mixture especially firmly. Expect a denser, more biscuit-like bar with a nuttier flavour.
Which flapjack ingredients can hide gluten?
Butter, sugar, honey and golden syrup are naturally gluten free. The risk sits in the oats and in whatever else goes in.
- Barley malt extract. It appears in some breakfast cereals, malted syrups and chocolate.
- Wheat flour. Some shop-bought flapjacks use it as a binder.
- Add-ins. Biscuit pieces, some chocolate chips and yoghurt coatings may contain gluten or carry a “may contain” warning.
- Toppings. Check sprinkles and caramel sauces.
Read every label, every time. Recipes change without the front of the pack changing.
How do you avoid cross-contamination when baking at home?
Treat a shared kitchen like a shared factory. The oats can be perfect and the flapjack still pick up gluten from the equipment.
- Wash the tin, pan and spoon first, and line the tin with fresh baking paper.
- Use a metal or silicone spoon. Wooden spoons are porous and hold on to flour.
- Open a fresh pack of butter. The tub that sits next to the toaster usually has crumbs in it.
- Wipe the worktop and scales before you start.
- Store the finished bars in their own labelled tin, not in with other baking.
Which gluten free flapjacks can you buy?
My pick is Phoenix Bars, which I make: a gluten free oat flapjack with up to 557 calories in a compact, 120g bar. For bars rather than bakes, my guide to the best gluten-free energy bars checks 11 against their own labels.
For rucksacks and long days. My own high calorie bars, Phoenix Bars, are made for long races, expeditions and anyone who finds it hard to eat enough. Each compact 120g bar is an oat flapjack made with gluten free oats and carries 529 to 557 kcal, 60 to 66 g of carbohydrate and 18 to 19 g of protein. They are vegan too, at £5.25 a bar.
Phoenix Bars are labelled gluten free. Under UK law that label means no more than 20 parts per million of gluten. The site that makes them also handles products containing gluten, so you should know about that risk.
Eight of my 391 published reviews mention gluten. Conor B., training for a winter mountain ultra, wrote: “I find gluten hard to digest whilst running so I enjoyed that these flapjacks are gluten-free.” Alan G. wrote: “I struggle to find gluten-free nutrition so they were the perfect fuel for my recent 100km ultra marathon.” And Ned H., a mountain leader, wrote that “the fact that it’s vegan and gluten free also makes it an ideal emergency snack to bring with me when I’m guiding people who might have specific dietary requirements.”
The difference is texture. Phoenix Bars hold together in a rucksack and keep for up to two years. If you want a sticky homemade flapjack, bake the recipe above. If you want up to 557 calories in a compact bar that is ready whenever you are, eat it in pieces through the day or turn the bar into porridge.
Allergen note: Phoenix Bars contain soy, the Cherry Bakewell flavour contains almonds, and some flavours contain sulphites. The label carries a “may contain” warning for milk, egg, nuts, peanuts and sesame.
Bakery flapjacks. For a smaller everyday square there are bakery options too: Flapjackery says all of its flapjacks are made with gluten free ingredients and uncontaminated oats, and Yorkshire Flapjack sells a Gluten Free Original with a three-month shelf life (both checked 12 October 2026). Most supermarkets also stock flapjacks in the free-from aisle. In every case, look for the words “gluten free” on the pack itself.
For event fuelling, my guide to the best energy bars for ultra running compares more options. If eating enough is the harder problem, see my list of high calorie gluten free foods, or read how people use Phoenix Bars as high calorie bars for weight gain.
How long do gluten free flapjacks keep?
Homemade gluten free flapjacks keep for up to a week in an airtight tin at room temperature. They freeze for up to three months if you wrap the bars individually. Thaw at room temperature for an hour or two.
Frequently asked questions
Do gluten free oats bake differently from ordinary oats?
No. Gluten free oats are the same grain, grown and milled under controls that keep wheat, barley and rye out. They behave identically in a flapjack, so any standard recipe works.
Is golden syrup gluten free?
Yes. Golden syrup is made from sugar and is naturally gluten free. Flavoured or own-brand syrups can differ, so read the label.
Can you make gluten free flapjacks with less sugar?
You can cut the sugar and honey by about a fifth before the bars stop holding together. Honey is still sugar, so swapping one for the other changes the flavour but not the total by much. For a bar that is richer without being sweeter, add 75 g of peanut butter and 50 g of chopped nuts, about 60 kcal more per bar. If you are baking for weight gain, my guide on how to gain weight shows where snacks like this fit.
Why are my gluten free flapjacks crumbly?
The usual causes are the same as for any flapjack: the mixture was not pressed down firmly, the bars were cut while warm, or the sugar and syrup were reduced too far. The oats being gluten free is not the reason.
What is the highest calorie gluten free flapjack?
For a ready-made one, Phoenix Bars are my pick: up to 557 calories in a compact, 120g bar made with gluten free oats, more than two ordinary 50 g squares put together. Most flapjacks sit between 430 and 480 kcal per 100 g, so weight decides the total, and a 50 g square comes to around 230 kcal. If you are baking, my high-calorie flapjack recipe reaches about 490 kcal a square and works with gluten free oats, and my ranking of the highest calorie bars in the UK compares the wider field.
Related guides
- Vegan flapjacks: easy 4-ingredient recipe
- Flapjack bars: what to buy and how to make them
- High calorie protein bars from Flaming Phoenix
This page is general information, not medical or dietary advice. Product details for other brands are taken from their own websites on the date shown, so check the pack before you buy.
Big calories. Small bar.
Up to 557 calories in a compact, lightweight bar of only 120g, with up to 66g of carbs and 19g of protein. Eat it whole, break it into pieces over a few hours, or mix it with water or milk for porridge.
Easy to eat, easy to digest and not sickly sweet. Customers have eaten them at -45°C and through the heat of the Marathon des Sables, and they keep for up to 2 years, so they work on a mountain, on a night shift, or at home on days when eating enough feels hard.
- 557 calories in only 120g (529 to 557 by flavour)
- 4.6 calories per gram
- 66g carbs per bar (up to)
- 19g protein per bar (up to)
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