Place the peeled and sliced Bramley apples in a large baking dish. Add the blackcurrants and caster sugar, then gently mix until the fruit is evenly combined.
750 g Bramley Apples, 300 g Blackcurrants, 60 g Caster Sugar
Place the plain flour, rolled oats, and light brown sugar in a mixing bowl. Pour in the melted butter and stir until the mixture forms moist crumbs and small clusters.
125 g Plain Flour, 125 g Rolled Oats, 150 g Light Brown Sugar, 125 g Butter
Spoon the oat crumble topping evenly over the apple and blackcurrant filling. Spread it loosely rather than pressing it down firmly, as this allows steam to escape and helps the topping become crisp.
Bake until the topping is deep golden and the fruit is bubbling around the edges of the dish (approximately 45 minutes). Leave the crumble to rest for 10–15 minutes before serving so the fruit juices can thicken slightly.
Notes
Blackcurrants: Fresh or frozen blackcurrants can be used. Frozen berries don't need to be fully defrosted; the crumble may need an extra 5 minutes in the oven.
Apples: Bramley apples give a soft, tangy filling. Granny Smith apples are a good alternative and are easier to find in the US.
Oats: Use regular rolled oats (old-fashioned oats in the US), rather than jumbo, instant, or steel-cut oats.
Don't press down the topping: Spoon it loosely over the fruit to help it become crisp and golden.
Check the fruit: The crumble is ready when the topping is golden and the fruit is bubbling around the edges. Check the apples are tender with a sharp knife.
Rest before serving: Leave for 10–15 minutes after baking to allow the fruit juices to thicken slightly.
Storage: Keep leftovers in the fridge for up to 3 days. Reheat uncovered in the oven for the crispiest topping.
Freezing: Freeze baked or unbaked for up to 3 months. Defrost overnight in the fridge before baking or reheating