Its a comfort food classic, and great for when theres still a bit of a chill in the air, but what does it take to make it just right?

If the proof of the pudding is in the eating, then crumble is comfortingly solid evidence that the best desserts aren’t delicate or even pretty: this isn’t a dish to stun social media, but it will momentarily silence the table. I can confidently say I’ve never, even in the darkest days of school dinners, met anyone who doesn’t like crumble.

Of course, you can stash just about any fruit you like under that buttery, sugary topping – though as Jesse Dunford Wood notes in his book Modern British Food, not all are appropriate – but the natural astringency of rhubarb, an underrated vegetable-identifying-as-a-fruit that fills the hungry gap between autumn apples and the first summer fruits, is the perfect complement, and a time-honoured partner for a jug of custard. (Dunford Wood also has strong opinions about the correct accompaniments to the crumble. He correctly identifies custard as the ideal).

When I asked for recipe recommendations for this column, someone scornfully responded, “Who uses a recipe for crumble?” They’re right: anyone can make a decent rhubarb crumble. But how do you make a perfect one?

The rhubarb

Rhubarb is the only fruit, or thing passing as a fruit, that sticks with us through the long, grey British winter, its candy-pink canes popping up in warm, dark sheds in Yorkshire, among other places, while the ground outside is still frozen solid – the sturdier, greener outdoor variety takes its place this month, and will continue to flourish, getting ever more monstrous in size, until the autumn.

Simon
Simon Hopkinson’s rhubarb crumble. Photograph: Felicity Cloake for the Guardian

Cookery writers and chefs, including the great Jane Grigson, tend to be snooty about outdoor rhubarb – “fat and stringy monsters, mostly all green and with just the faint remembrance of pink”, as Simon Hopkinson memorably puts it in Second Helpings Of Roast Chicken – but I suspect that’s as much to do with its unremarkable looks as its flavour. The spindly, blushing-pink stalks of January and February are easy for the camera to love, while the olive trunks as thick as a terrier’s ankle are far less Instagram-friendly. They still taste great, however – and, as one of the easiest things to grow in pots that I know, deserve a bit more love from us ingrates in the food media.

Rukmini
Rukmini Iyer’s rhubarb crumble. Photograph: Felicity Cloake for the Guardian

Whichever you happen upon (and if you’re reading this at the time of publication, it’s likely to be the first of the outdoor crop), it will give off a lot of liquid as it cooks; rhubarb just does. Some recipes seek to remedy this by pre-baking it (as in Rukmini Iyer’s aptly named book The Roasting Tin), or tossing it with cornflour to help absorb the liquid, as Jane Baxter suggests in the Riverford Farm Cook Book. The cornflour gives the filling an unexpectedly thick, almost gummy quality, while the part-baked rhubarb begins to caramelise around the edges by the end of cooking. Plus, it strikes us as we tuck in, what on Earth is wrong with rhubarb juice anyway? Surely one of the great joys of a rhubarb crumble is the chance to watch science in action as that sour, pinkish syrup turns your custard into a curdled mess. If you’re less keen, I’d advise following Iyer’s advice and baking the filling, covered in foil, for 15 minutes before adding the topping.

You’ll need to sweeten the filling somehow, but don’t go overboard: the key to success is to maintain the contrast between tangy fruit and sweet topping. The neutral sweetness of white sugar is ideal here, to allow the rhubarb to shine, but seeing as I’m using demerara in the topping, it makes sense to stick with that here, too.

… is not the only fruit

Anna
Anna Jones’s rhubarb and apple crumble. Photograph: Felicity Cloake for the Guardian

For some reason, rhubarb has gained a reputation as a fruit that pairs well with strawberries. I’m instinctively repulsed by the idea, but after reading in the Riverford book that “Jane used to think that cooking strawberries was an abomination, but this combination came as a very pleasant surprise”, I’m prepared to give it a whirl. Turns out it’s not just me: everyone hates it. Perhaps it’s just too early in the season, but the baked strawberries have an odd, mushy texture, and very little flavour at all. Always nice to have one’s prejudices confirmed.

The apple and rhubarb combination suggested by Anna Jones in her first book, A Modern Way To Cook, proves more popular, though using them in a 1:1 ratio means the softer rhubarb has a tendency to get lost among the more solid chunks of apple. If you must mix your fruits, however, this is probably the best option.

The flavourings

One thing that does go with rhubarb is ginger: Iyer grates fresh root into her filling, and also adds orange zest and juice, as does Jones. I like the ginger in particular, but some testers find it a bit fiery, so I’m going to leave it out, while recommending anyone who enjoys the warming heat of ginger should be brave enough to give it a try.

Hugh Fearnley-Whittingstall recommends pairing rhubarb with sweet cicely: “As well as adding a lovely, aromatic edge to a dish, the aniseedy leaves make tart fruits seem sweeter, which means you can use less sugar.” Sadly, I don’t happen to have any in the garden, but if you do, this might also be a good option. I’m less sure about Gregg Wallace’s rhubarb and port idea, but if anyone else has time to try it, I’d love to hear your thoughts.

The topping

Jane
Jane Baxter’s rhubarb crumble. Photograph: Felicity Cloake for the Guardian

Dunford Wood may be right in thinking that tropical fruits have no place in a crumble, but he loses some credibility with his attempts to take back control by cooking the two elements separately: “fewer soggy crumble issues and more consistency with the fruity filling, I find.” This is disappointing indeed: as Baxter’s second rule of crumble states, “Never cook the two parts separately or deconstruct the crumble in any way. This is an abomination.” (Like cooked strawberries, in fact.)

Delicious as Dunford Wood’s biscuity, crunchy, honey-sweet topping is, it lacks the wonderfully soggy layer that forms as the fruit steams beneath; one of the hallmarks of a proper crumble, we all agree. If you want a fancy, restaurant-style dish, by all means follow his lead, but make sure you serve it with crème anglaise, rather than besmirching the noble name of Bird’s with such foolishness. (And if you want your crumble in a hurry, Anna Jones’ super-quick pan version, which can be put together in less than 15 minutes, is an excellent version.)

Chef
Chef Steps’ rhubarb crumble. Photograph: Felicity Cloake for the Guardian

Many recipes add oats or ground almonds to their crumble mixtures. Both have their fans – and their downsides. Too many chewy, stodgy oats, and the topping becomes a flapjack; more ground almonds than flour, and it falls apart at the first touch of the spoon (though the American website Chef Steps has a clever, flour-free version using ground almonds and egg yolks that may be of interest to coeliacs). The sweetness of almonds does go well with rhubarb, however, so I’ll be using a smaller proportion, and topping the dish with chopped almonds, an idea stolen from Jones, though I won’t be using coconut oil or sugar as she suggests. Far too exotic.

Both dark and light brown sugars have their merits in this context, but we’re all smitten by the crunch of Dunford Wood’s demerara-flecked topping, even if it’s never seen a stick of rhubarb in its life. A proper school-style crumble should be satisfyingly solid, almost craggy, which requires a generous amount of butter and a splash of water to bring it together; chill it before use to help it clump in the correct fashion.

Iyer and Hopkinson both add ground ginger to their crumble mixture, Delia Smith sticks in cinnamon as well, Edd Kimber cardamom and Baxter crushed amaretti, but I think it’s delicious enough on its own. Serve with custard, preferably Bird’s, and preferably with a skin as thick as a rhinoceros hide, or plain ice-cream. Also delicious cold for breakfast.

Perfect rhubarb crumble

Prep 10 min
Chill 10-20 min
Cook 40 min
Serves 6-8

800g rhubarb
40g demerara or white sugar
25g skin-on almonds, roughly chopped (optional)

For the crumble topping
150g plain flour
75g ground almonds
170g chilled, unsalted butter, grated or diced
75g demerara sugar
¼ tsp salt

Heat the oven to 200C/390F/gas 6. Chop the rhubarb into roughly 3cm lengths and put it in a medium baking dish just big enough to hold it all. Pour over the sugar and toss together well.

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