Place the flour, sugar and salt in the bowl of your food processor and pulse for a few seconds to mix.

Add the very cold butter cut into small cubes. Pulse to mix until you get very small crumbs of butter.

Add the cold Water a little bit at the time while pulsing. Stop when a rough dough starts to come together.

Bring the pastry together into a disk and place between two sheets of baking paper.

Using a rolling pin, roll into a large disk that is about 4 mm (⅙ inch) thick. Place in the fridge to chill for at least 1 hour.

In a large bowl, toss together the blackberries, lemon zest and lemon juice.

Mix in the cornstarch and sugar; the blackberries should be evenly covered with all the other ingredients.

Preheat your oven on 180 degrees Celsius / 350 degrees Fahrenheit.

Prepare a flat tray with a sheet of baking paper or baking mat.

Remove the baking paper and place the chilled pastry over the prepared baking tray.

Spread the almond meal over the pastry in an even layer, leave about 2 to 3 cm clear around the edges.

Top with the blackberry mixture, spread into an even layer.

Pick up the edges of the pastry and fold them over, slightly covering the outer ring of blackberries.

Make sure there are no gaps within the folded pastry where the filling could escape.

Optional: lightly whisk the egg in a small bowl and brush it over the rolled edges of pastry.

Sprinkle the crust with some raw sugar.

Bake for 35 to 40 minutes, or until the edges of the pastry are golden and the blackberries are very soft.

Leave to cool down on a wire rack before serving.