Everyone loves a crumble. But my Rhubarb and Blueberry Crumble is something a little special. Carefully created to ensure the most deliciously textured crumble topping and fruit that shines with every mouthful, it is gluten free dessert heaven. Optional dairy free and vegan too!
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Rhubarb and Blueberry Crumble – Something a little special!
Gotta love a crumble! Right? But my gluten free Rhubarb and Blueberry Crumble is truly special. The unique tartness of sweetened rhubarb compote, paired with little bites of blueberry that pop in the mouth to release sweet berry juice. All topped with a soft yet crunchy, buttery crumble layer, baked until golden. Serve with creamy vanilla custard, cream or ice cream for crumble dessert perfection.
Best of all… My Rhubarb Crumble with Blueberries is easy to make and bake, and no one will EVER know it’s gluten free… And that’s a PROMISE.
Rhubarb Crumble or Rhubarb ‘Crisp’ – what’s the difference?
Check the internet for crumble recipes and you’ll find something very similar called fruit ‘crisp’ in amongst the list. So… What’s the difference?
Fundamentally, a crumble is a dessert that has a baked fruit base topped with a thick crumbly ‘streusel’-like layer made from flour, butter and sugar. A crisp is similar… But the topping (which forms a much thinner layer) includes oats and sometimes nuts.
If you’ve already had a peak at the recipe card, you’ll see that I’ve included oat flour in my recipe for Rhubarb and Blueberry Crumble… So… Is it a Crumble or a Crisp?
I’m going most definitely with crumble for 2 reasons:
- The crumble layer is thick and substantial.
- Using oat flour is not the same as using oats. The overall texture is very different. While the oat flour offers extra flavour and a little ‘creaminess’ of texture to the crumble, it remains very much part of the flour blend.
Ingredients for making Rhubarb and Blueberry Crumble
Gluten Free Flour Blend
Although I used my Gluten Free Alchemist white flour blend A as the base for my crumble topping, alternative gluten free flour blends should work just as well. For crumble, I personally prefer a white flour blend. It just gives a more defined colour contrast with the fruit filling. Also, white blends tend to have a milder flavour, allowing the fruit to truly shine.
If you are not gluten free, just use standard white wheat flour.
As already explained, adding oat flour offers more depth of flavour. But it also gives a slightly softer and creamier texture to the crumble top…
If you are unable to eat oats however, that’s fine. Simply use the same additional weight of your chosen gluten free flour blend in the recipe.
Adding xanthan gum to gluten free crumble mix is entirely optional. And I guess you may be wondering why it’s there at all? Well… I’ve made gluten free crumbles with and without xanthan gum and what it offers is a touch of ‘body’ and a slightly greater ability for the mixture to ‘clump’ a little. In crumble world, I think that counts! And while the amount used is very small, I honestly think it makes a difference to the final result.
One of the things I always loved about rhubarb crumble before gluten freedom, was that the crumble had little clumps of crispiness. The xanthan gum encourages that texture.
While I appreciate that baking powder in crumble isn’t a ‘standard’ ingredient, it does give the topping a little lightness. And I suspect, supports the xanthan gum in creating little extra pockets of bite.
If using a commercial flour blend to make your rhubarb crumble with blueberries, you have the option to use self-raising flour and leave out the baking powder.
Because the butter has to be rubbed into the flour, it needs to be of the ‘block’ variety. ‘Spreads’ simply won’t cut it!
I personally prefer to use unsalted butter and add a pinch of salt to the flour blend. But if you like your rhubarb and blueberry crumble to have a salty edge, feel free to use salted butter instead.
The recipe offered does not over-sugar the fruit base or topping. I hate anything over-sweet and aim for balance that allows the sweetness and complexity of the fruit flavours to be the star of the show.
My particular Rhubarb and Blueberry Crumble uses both caster sugar (of the golden variety) and light soft brown sugar. This gives a more natural and slightly caramel sweetness to the bake. However, feel free to use standard caster sugar across the board if that’s what you like, or have to hand.
The Demerara sugar sprinkled on the top gives a little extra crunch and sparkle.
Rhubarb tends to be a seasonal vegetable… (Yes… It’s a vegetable not a fruit). And while it is most freely available in the summer, if you live in a part of the world where you can get early or ‘forced’ rhubarb, grab it while you can. In the UK we are really lucky to have Yorkshire forced rhubarb which appears from around mid-January until early March. It’s deep pink in colour and full of flavour. And it’s totally perfect for any and all rhubarb recipes including Rhubarb and Blueberry Crumble.
Apart from being super good for you, blueberries are utterly delicious. They pair particularly well with rhubarb, offering sweetness alongside the rhubarb tang. And prepared properly for the crumble (see below), will maintain shape, so that you get little ‘pops’ of juicy blueberry as you munch.
Corn starch (known in the UK as cornflour)
Corn starch (aka UK cornflour) is the white starchy powder that is often used for thickening sauces, etc. But it is also a genius addition for blueberries in crumble to be sure they don’t all burst and lose their juice during cooking. And… the cornflour will help the filling remain thick under the crumble too. It’s a little trick that I picked up from Feast Glorious Feast.
To make the magic happen, simply coat the blueberries in corn starch (not the standard flour-blend) before folding them gently into the rhubarb compote.
Top tip for the best rhubarb and blueberry crumble topping
Since I’ve made a few rhubarb and blueberry crumbles in my time, here’s a little tip that helps to make an epic pudding…
…When you’ve finished making the crumble topping and it’s all stirred through, pop it in the fridge until you are ready to use it. The cold helps the butter ‘flecks’ to stay solid until it hits the oven. And that means your crumble will have a better, softer and more crumbly texture.
Avoiding a ‘watery’ rhubarb filling
You have two options for avoiding a ‘watery’ rhubarb filling. But the route you take will depend on whether you prefer a crumble with a thick compote base or discernible pieces of fruit. I personally prefer the compote option for a Rhubarb and Blueberry Crumble, but it seems only fair to explain both…
- For a rhubarb compote – Simmer the sugar and rhubarb on the hob, until it has reduced to a thick and fruity mix. This will ensure any excess moisture has evaporated before it hits the oven.
- If you prefer your rhubarb in pieces – It will still be necessary to part-cook the rhubarb in a saucepan, but the aim is merely to soften, rather than crush. Simply simmer in small pieces for about 6 minutes… Then carefully remove the rhubarb from the pan into the oven dish (using a slotted spoon)… And finally, simmer the remaining juice and sugars left in the pan until they have reduced to a syrup, which can be poured over the fruit. Leave to cool before adding the blueberries and crumble top… Then bake until golden.
Is this gluten free Rhubarb and Blueberry crumble recipe safe for Coeliacs (Celiacs)?
Yes… Providing the crumble top is made with a gluten free flour blend, then it is entirely safe for people with Coeliac Disease (Celiac). Just remember to double check the ingredients label of the baking powder to be sure it has no hidden gluten. And if you are sensitive to eating oats, sub them with the same weight of plain flour blend.
Make Rhubarb Crumble with Blueberries dairy free and vegan
To make my Rhubarb Crumble with Blueberries dairy free and Vegan, the only switch needed is the butter. Simply sub butter for a dairy free and vegan block alternative. It is important that it is a block, as it will need to be rubbed into the flour. I recommend either Stork Baking Block or Flora Baking Block.
Get ahead… What can I prepare in advance?
One of the great things about Rhubarb and Blueberry crumble is that it can be prepped ahead of time. Prep the crumble top and pop it in the fridge (up to 3 days ahead)… And prep the rhubarb compote for the base (also up to 3 days ahead)…
Then on the day you want to eat it, coat and fold the blueberries into the compote… Top with crumble… and bake! Just remember to keep the crumble topping in the fridge until ready to cook for the best texture and crunch.
How to serve Rhubarb and Blueberry Crumble
This crumble is at its best served warm, with cool vanilla custard, vanilla ice cream or cream… Double cream, single cream, whipped or clotted. All and any are good!
My personal favourite is a good homemade or ‘finest’-style custard… Not the thick and sticky very yellow variety. Crumble loves a silky custard that flows over and settles into the nooks and crannies of its unevenness.
How long does Rhubarb Crumble keep?
The best crumble is without doubt served fresh and just baked. But if there’s some left, it certainly won’t go to waste… One of my favourite fridge raids is for cold crumble and custard. There’s something about the firmed-up, slight chewiness of cold crumble that my taste buds adore!
To store and raid… Let the crumble go cold at room temperature, before covering with a lid or clingfilm and popping in the fridge. If it isn’t devoured on the next sneaky visit to the fridge, it should last for 2 to 3 days.
Eating cold is optional of course! If you prefer leftover crumble warm, simply pop in the microwave for a few seconds. It won’t have quite the same texture as when first baked. But it will be delicious nonetheless.
Ready to make Gluten Free Rhubarb and Blueberry Crumble?
And that’s all there is to it… The perfect Rhubarb and Blueberry Crumble with a gluten free crumble top. I hope you love it. If you have any questions that I haven’t answered, feel free to make contact. You can leave a comment below or email me using a contact form.
And if you do make it and love it, please like or rate the recipe. Even better… take a quick photo and share on social media (being sure to tag me in so that I find it). #glutenfreealchemist. Facebook, Instagram, Pinterest and Twitter.
And if rhubarb isn’t your thing, I also have a DIVINE Apple and Blackberry Crumble too!
Happy crumble making
Rhubarb and Blueberry Crumble (gluten free)
- large saucepan
- oven proof serving dish(es)
- oven + hob
Gluten Free Crumble Top
- 200 g white gluten free plain flour blend eg. Gluten Free Alchemist Blend A – See NOTES
- 100 g oat flour if you are intolerant to oats, use an additional 100g white gluten free flour blend
- ¼ tsp xanthan gum optional
- 2 tsp baking powder gluten free
- pinch fine sea salt
- 150 g unsalted butter (or dairy free block alternative) – cold and cubed
- 100 g golden caster sugar
- 50 g soft light brown sugar or if preferred sub with additional caster sugar
- 2 tbsp Demerara sugar to sprinkle
Rhubarb and Blueberry Filling
- 130 g golden caster sugar
- 700 g rhubarb washed and cut into 1 inch/2½ cm lengths
- ½ tbsp cold water
- 140 g fresh blueberries
- ½ tbsp corn starch UK cornflour
Greasing the oven-proof dish
- a little butter/dairy free spread
Gluten Free Crumble Top
- In a large bowl, weigh and mix together the flours, xanthan gum (if using), baking powder and salt.
- Add the cold, cubed butter and (using finger tips) rub into the flour mix until it resembles coarse sand.
- Add and stir through the golden caster and light brown sugar.
- Set aside in the fridge until ready to use.
Rhubarb and Blueberry Filling
- Place the sugar and rhubarb pieces into a large saucepan with half a tablespoon cold water.
- Place on the hob over a low heat and stirring continually, gradually bring to a simmer. As the rhubarb heats, it will start to release liquid. The sugar will also dissolve.
- Allow to simmer, stirring intermittently for about 30 minutes. The rhubarb will largely disintegrate and the syrup will reduce, leaving a thick compote.
- Once cooked, remove from the heat and allow to cool down to a ‘warm’ temperature. (Stirring frequently will help the compote to cool more quickly).
- While the rhubarb is cooling, prepare the blueberries by mixing them with the corn starch in a shallow bowl. The blueberries should pick up a coating of corn starch.
- Prepare the oven-proof serving dishe(s) by greasing the inside with a little butter.
- When the rhubarb has cooled enough, add the floured blueberries and gently fold through.
- Immediately transfer the fruit to the prepared serving dishe(s).
Topping and baking the crumble
- Pre-heat the oven to 180 C/350 F/Gas 4.
- Top the fruit base with the chilled crumble mixture (it should be generously topped and completely covered).
- Sprinkle with Demerara sugar to add extra crunch.
- Bake for about 40 to 45 minutes until the top is golden and the fruit is bubbling.
- Leave to cool for 5 to 10 minutes before serving warm with a side of custard, cream or ice cream.
© 2019-2023 Kate Dowse All Rights Reserved – Do not copy or re-publish this recipe or any part of this recipe on any other blog, on social media or in a publication without the express permission of Gluten Free Alchemist