Method

​1 Preheat the oven to 180°C/fan 160°C/gas mark 4.

2 Topping: place the gluten-free flour in a large mixing bowl and gently rub in the butter using your fingertips until it resembles fine breadcrumbs. Stir in the sugar and gluten-free oats.

3 Filling: place the blackberries into a heatproof bowl and sprinkle the sugar (to your taste). The blackberries will generate plenty of juice as they cook so there’s no need to add any water.

4 Assemble: sprinkle the crumble mixture over the blackberries. Use a fork to evenly spread the topping (don't press down too hard).

5 Cook on a high shelf in the oven for 30–40 minutes or until light brown colour on the top. Serve your crumble hot with lashings of custard or double cream and enjoy!