Berry Crumble Tart — a crisp tart shell, jammy berries and a buttery crumble lid

i. Origin & history

The berry crumble tart is a modern hybrid, and it is the product of two traditions meeting. The fruit tart in pastry is an old and central part of French baking, from the rustic tartes aux fruits of country households to the glazed, pastry-cream-filled tarts of Parisian shops. The crumble, on the other hand, is British: a rubbed-in topping of flour, butter and sugar baked over fruit. It is often said to have become popular during the Second World War, when it was an economical alternative to pastry under rationing, though crumb toppings for fruit certainly existed before that.

Central Europe had its own version of the idea much earlier. German and Austrian bakers have long scattered Streusel — a crumble of butter, sugar and flour — over yeast cakes and fruit tarts, and the Streuselkuchen and plum or rhubarb Streusel tarts of Germany are close relatives of this tart. Polish and Alsatian bakers use similar toppings.

In France the English word "crumble" was adopted wholesale in the late twentieth century, and le crumble became a staple of bistro dessert menus and home cooking. It was a short step for French pastry shops to put the crumble on top of a tart, and the tarte crumble — with apples, rhubarb or red berries — is now a common sight in bakeries and supermarkets across France.

The appeal is practical as much as anything. A crumble on top hides imperfect fruit, needs no lattice or glaze, holds the juices in and gives a contrast of textures — crisp base, soft jammy fruit, crunchy top — that a plain open tart lacks. It also slices cleanly and travels well, which a dish of crumble does not.

ii. How to keep the base crisp under juicy berries

Berries release a great deal of juice as they bake, and a pastry case holding them is in constant danger of turning soggy. Three measures together prevent it. First, the case is blind-baked before filling, so the pastry has set and partly dried before it ever meets the fruit. Second, a thin layer of ground almonds mixed with sugar is scattered over the base. As the berries release juice, the almonds absorb it, turning into a soft, frangipane-like layer instead of letting the liquid soak into the pastry. Pastry chefs use semolina or crushed biscuits the same way.

Third, the berries are tossed with cornflour, which thickens the juice as it boils. As in any fruit pie, the cornflour only works when the juice actually bubbles, so the tart must be baked until you see thick juice bubbling through gaps in the crumble — not just until the topping is browned.

The crumble itself needs a different balance from a crumble served in a dish. Because it sits on a relatively thin layer of fruit and must stay crisp for a day or two, it is made with a higher proportion of butter and sugar, plus a little ground almond or oats for crunch. Rubbing cold butter into the dry ingredients until the mixture forms irregular clumps gives a topping that bakes into crisp clusters; overworking it produces a sandy, flat lid.

Frozen berries work well, but they should go in still frozen. Thawed berries collapse and release their juice before the tart even reaches the oven.

iii. Ingredients

Makes 8 servings · scroll the side panel to adjust

• 200 g plain flour, for the pastry
• 60 g icing sugar
• 1 pinch salt
• 110 g cold unsalted butter, diced, for the pastry
• 1 egg
• 500 g mixed berries (raspberries, blueberries, blackberries)
• 60 g caster sugar, for the fruit
• 1½ tbsp cornflour
• 1 tsp lemon zest
• 40 g ground almonds, for the base
• 1 tbsp caster sugar, for the base
• 100 g plain flour, for the crumble
• 40 g ground almonds or rolled oats, for the crumble
• 70 g demerara or light brown sugar
• 80 g cold unsalted butter, diced, for the crumble

Any mix of berries works; raspberries bring sharpness, blueberries hold their shape and blackberries add depth of colour. Strawberries are best halved and combined with others, as they turn soft and watery on their own. Frozen berries can be used straight from the freezer. Demerara sugar gives the crumble a crunchier finish than caster. For a gluten-free tart, use a 1:1 gluten-free flour blend in both pastry and crumble and choose almonds rather than oats. Good shop-bought sweet shortcrust can replace the homemade pastry.

iv. Method

1. For the pastry, rub the flour, icing sugar, salt and cold butter together to fine crumbs, then add the egg and bring together into a dough. Flatten, wrap and chill for 45 minutes.
2. Roll out to 3 mm and line a 23 cm loose-bottomed tart tin. Prick the base and chill for 20 minutes. Heat the oven to 190 °C (375 °F), fan 170 °C.
3. Blind-bake with paper and baking beans for 15 minutes, then remove them and bake for 5 minutes more until the base looks dry and pale golden. Reduce the oven to 180 °C (350 °F), fan 160 °C.
4. Meanwhile make the crumble: rub the flour, ground almonds or oats, sugar and cold butter together until the mixture forms damp clumps the size of peas. Chill until needed.
5. Toss the berries with the caster sugar, cornflour and lemon zest. Mix the 40 g ground almonds with 1 tbsp sugar and scatter evenly over the warm pastry base.
6. Pile the berries into the case in an even layer and scatter the crumble over the top, leaving a few small gaps.
7. Bake for 35–40 minutes, until the crumble is golden and the berry juices are bubbling thickly through the gaps. Cover loosely with foil if the topping browns too quickly.
8. Cool in the tin for at least 1 hour so the juices set, then remove from the tin and slice.

v. Tips & common mistakes

• Always blind-bake the case. Raw pastry under wet berries stays pale and doughy. Even a short blind bake makes a crisp base.
• Do not skip the almond layer. It soaks up excess juice and turns into a soft, nutty layer that protects the pastry.
• Use berries from frozen. Thawing frozen berries turns them to mush and floods the case before it bakes.
• Keep the crumble cold and lumpy. Chill it until the last minute and leave large clumps; they bake into crunchy clusters.
• Bake until the juice bubbles. The cornflour thickens only when the juice boils. A tart pulled too early will be runny when cut.
• Let it cool before slicing. Warm, the filling runs. After an hour it sets enough to cut clean wedges.

vi. Variations

The same tart works with almost any fruit. Apple and blackberry is a British autumn favourite; rhubarb and strawberry is the classic spring combination in France and Germany; plum or apricot with a cinnamon crumble mirrors the German Streusel tarts. Adding a thin layer of frangipane under the fruit instead of the ground almonds turns it into something closer to a Bakewell, and a handful of chopped hazelnuts in the crumble adds flavour.

If you prefer fruit and crumble without pastry, see the apricot crumble and the oat-topped ginger peach crisp. For a fruit tart without a topping, the pear tart and Bakewell tart are close cousins, and the Polish szarlotka takes apples between layers of crumbly pastry.

vii. Serving & storage

Serve the tart warm or at room temperature, in wedges, with vanilla ice cream, crème fraîche, custard or lightly whipped cream. It is an easy summer dessert for gatherings and picnics, because it can be baked in the morning and carried whole, and it is equally good in winter made with frozen fruit.

Keep the tart covered at room temperature on the day it is baked, then in the fridge for up to 3 days. Re-crisp slices in a 180 °C (350 °F) oven for 8–10 minutes. The pastry case can be blind-baked a day ahead and the crumble made and refrigerated for up to 3 days or frozen for up to 3 months. The baked tart freezes for up to 2 months; thaw at room temperature and warm through before serving.

ix. More from French

• Pear Tart — tarte Bourdaloue
• Almond Tart — tarte aux amandes
• Flaugnarde — fruit baked in batter
• Apricot Crumble — stone fruit under crumble
• Bakewell Tart — British almond-jam tart
• Szarlotka — Polish apple cake