Baking a Rustic Blackberry and Apple Crumble

Few things sum up a British autumn quite like a warm crumble pulled from the oven, its edges bubbling with dark purple juice. Blackberry and apple is the classic pairing for good reason: the sharp, yielding apple softens the wild, faintly winey tang of the bramble fruit, and a buttery oat topping brings everything together. Better still, the ingredients are often free for the taking — a hedgerow walk and a few windfall apples will do it. Here is how to make the most of the season.

Picking Your Blackberries: A Hedgerow Primer

The bramble season runs from late August through to October, and a warm, damp summer usually means a heavy crop. Look for berries that are deep, glossy black and come away from the stem with the gentlest of tugs; anything that resists is underripe and will taste sour, while a dull, squidgy berry is past its best. Pick above knee height where you can, partly to avoid anything a passing dog has left behind, and steer clear of busy roadside verges where exhaust fumes settle on the leaves.

Brambles bite, so wear long sleeves and gardening gloves, and take a shallow container rather than a bag — deep punnets crush the fruit and leave you with jam before you have even started. A word on quantity: you want roughly 600g of berries for this recipe, which sounds a lot until you realise how much gets eaten on the walk home.

What You Will Need

This makes enough for six generous portions in a roughly 2-litre ovenproof dish. Have everything weighed out before you start — crumble comes together quickly.

• For the fruit: 600g foraged blackberries, 500g peeled, cored and sliced apples, 100g caster sugar (adjust to taste), the zest and juice of one lemon, and 1 tablespoon of cornflour
• For the topping: 200g plain flour, 100g cold unsalted butter, 75g porridge oats, 75g demerara sugar, a good pinch of fine salt, and 1 teaspoon of ground cinnamon or mixed spice

On the apples: a mix is best. Bramleys break down into a soft, fluffy purée that thickens the juices, while a couple of Cox's or Egremont Russets hold their shape and add perfume. All-bramley crumbles can turn to mush; all-eaters can stay too firm.

Preparing the Fruit

Give the berries a gentle rinse in a bowl of cold water and lift them out rather than tipping them into a colander, which bruises them. If you are at all worried about the small larvae that sometimes inhabit wild berries, soak them for ten minutes in lightly salted water — they will float free — then rinse well. Don't overdo the salt or you will taste it later.

Tumble the drained berries and sliced apples with the sugar, lemon zest and juice, then stir through the cornflour. The lemon is not optional: it sharpens the flavour and helps the fruit set into a glossy, spoonable compote rather than a watery puddle. Taste a berry and a slice of apple as you go and trust your palate — a wet, cold season means tarter fruit and a little more sugar.

The Crumble Topping

Cut the cold butter into cubes and rub it into the flour with your fingertips until it resembles coarse breadcrumbs, or pulse it briefly in a food processor and finish by hand. Stir in the oats, demerara, salt, spice and a little extra lemon zest if you have it. The texture should be claggy and uneven, with some pea-sized lumps — those lumps are what give you the crunchy, biscuity peaks that everyone fights over. If it looks like fine sand, add another knob of butter; if it is greasy, a spoonful more flour.

Assembling and Baking

Tip the fruit into your dish and spread it level. Scatter the topping over in an even layer, then press a few loose handfuls together as you go to create clusters. Resist the urge to pack it flat — you want air and texture. Sit the dish on a baking tray lined with parchment to catch the inevitable overflow.

Bake at 180°C (160°C fan, gas mark 4) for 35 to 45 minutes, until the topping is deep golden and the juices are bubbling up thickly around the edges. If the top is browning faster than the fruit is cooking, lay a sheet of foil loosely over it. Then — and this matters — leave it to stand for ten minutes before serving. The filling needs to settle, and a mouthful of molten blackberry juice is a genuine hazard.

Serve with proper custard, cold pouring cream or a scoop of vanilla ice cream. A crumble is at its best within an hour of leaving the oven, though a bowl of it cold the next morning is a fine, if slightly guilty, pleasure.

Using Up the Surplus

If you have picked more than you can bake, the freezer is your friend. Spread clean berries on a tray in a single layer, freeze until solid, then bag them up — they will keep for a year and rattle straight into crumbles and pies without clumping. For a more permanent fix, blackberry and apple jam is made with equal weights of prepared fruit and sugar, a good squeeze of lemon and a slow simmer until a spoonful wrinkles on a chilled saucer. Strain the same fruit through muslin with sugar and a splash of lemon juice and you have a cordial that tastes of September, diluted with sparkling water whenever you need reminding.