Basque-style blackberry pie

1. Line the base of a 23cm springform cake tin with baking parchment. Put the blackberries in a small saucepan with 25g caster sugar and 4 tbsp water. Set over a medium heat and bring to the boil. Simmer gently, crushing the berries with the back of a wooden spoon, for 6-8 minutes, until thick and jammy. Add the lemon juice and set aside to cool.

2. Mix the egg yolks in a small bowl, then transfer 1 tsp to another bowl; stir in 1 tbsp water to make a glaze and set aside. In a large bowl, combine the remaining 250g sugar and the butter with a wooden spoon. Add the flour and roughly combine, then mix in the egg yolks to make a smooth but sticky dough. Cover and chill for 20 minutes.

3. Preheat the oven to 180˚C, gas mark 4. With a floured spoon, drop tablespoons of ½ the dough over the base of the parchment-lined cake tin. With floured fingers, spread it out in the tin and pat down well. Smooth over the cooled blackberry mixture, then carefully top with the remaining dough, using a palette knife to smooth the surface. Brush with the egg yolk glaze, then score diagonal lines across it to make a diamond pattern.

4. Bake for 40 minutes, covering the top loosely with foil if it colours too much. Leave to cool in the tin before running a knife around the edge and removing. Dust with icing sugar and slice into wedges to serve with cream, if liked.