Air Fryer Recipe
Blackberry Crumble Bars
Blackberry crumble bars bring together sharp, juicy fresh blackberries and a sweet, buttery crumble, making them a lovely little treat for the air fryer.
Ingredients
- 200g plain flour
- 100g granulated sugar
- 120g unsalted butter, chilled and cubed
- 1 tsp vanilla extract
- Pinch of salt
- 300g fresh blackberries
- 50g rolled oats
- 30g light brown sugar
- Zest of 1 lemon
- 1 tbsp cornstarch
Method
- In a mixing bowl, stir together the flour, granulated sugar and a pinch of salt. Add the chilled, cubed butter and vanilla extract, then blend until the mixture looks like coarse crumbs.
- Set aside 1 cup of the crumble mixture for the topping. Press the rest evenly into the bottom of a greased and lined air fryer-friendly baking pan.
- In a separate bowl, mix the blackberries, light brown sugar, lemon zest and cornstarch. Spoon and spread this over the crumble base.
- Combine the reserved crumble mixture with the rolled oats, then scatter it over the blackberry layer.
- Preheat the air fryer to 160°C (320°F) for 5 minutes. Put the baking pan inside and air fry for 20-25 minutes, until golden brown and bubbling.
Why this works in an air fryer
The air fryer’s compact convection drives moisture off the crumble topping quickly, so the butter-rich crumbs brown before the blackberry filling overcooks. Cornstarch thickens the berry juices as they bubble, while minimal mixing keeps gluten development low for a short, crumbly base rather than a tough biscuit layer.
Equipment notes
Assumes an 18–20cm air-fryer-safe metal tin in a 5–6 litre basket. In a single-drawer air fryer, centre the tin and rotate it halfway if one side colours faster; in dual-zone models, the smaller drawer and reduced airflow often need 3–5 extra minutes, especially if the other drawer is running.
Common pitfalls
- Top is dark but the blackberry layer is not bubbling at the edges: the element is too close or the drawer runs hot; cover loosely with foil, drop to 150°C and cook until the filling visibly bubbles.
- Base looks greasy and compact rather than sandy: the butter softened too much before cooking; chill the pressed base in the tin for 10 minutes next time and avoid overworking the crumble.
- Filling leaks out in a thin purple syrup when sliced: berries were wet or the bars were cut hot; pat berries dry, toss until the cornstarch is evenly dispersed, and cool completely before cutting.
- Edges are set but the centre sags when lifted: the tin is too deep or the layer is too thick; use a wider shallow tin and add 4–6 minutes at 150°C so the centre can set without burning the topping.
Variations & substitutions
- Frozen blackberries can be used from frozen; add 1 extra teaspoon cornstarch and expect 3–5 minutes longer because they release more water.
- Swap half the blackberries for raspberries or blueberries; raspberries soften faster, while blueberries usually need the full cooking time to burst and thicken.
- Replace up to half the plain flour with wholemeal flour; the base tastes nuttier but browns a little faster, so check from 18 minutes.
- Use orange zest instead of lemon zest; it gives a rounder, less sharp flavour and does not change the cooking time.
Storage & reheating
Keep cooled bars in an airtight container in the fridge for up to 3 days, then reheat in the air fryer at 150°C for 3–5 minutes to re-crisp the crumble.
Nutrition
Calories: 250
