The zest and juice of one orange
120g/4oz plain flour
2 tbsp muscovado sugar
120/4oz unsalted butter, cold
Heat your oven to 180C/350F/Gas4.
Put the blackberries, orange zest and juice into a bowl and toss together gently using your fingers. Spoon into an ovenproof dish.
In a separate bowl, sieve the flour and add the sugar; stir together to combine.
Cut the butter into little cubes, add to the flour-sugar mixture and crumble between your finger until you have the texture of sand. If you have a few lumps, all the better.
Sprinkle the mix over the blackberries and place on the middle shelf of the oven. Bake for 20-25 minutes or until the berries are bursting around the sides and the top is golden brown.
Remove from the oven, allow to cool slightly and serve.