First, make the blackberry compote. Place the berries into a wide-based saucepan, cover, and heat over a low heat. Don’t be tempted to add water, the berries will sweat and soften in their own juices. Once the berries are simmering, turn up the heat and add the sugar. Cook for about 10 minutes, stirring regularly, until the berries begin to thicken a little. Combine the cornflour and water in a small bowl then drizzle this over the bubbling berries. Cook for another minute until the mixture thickens. Remove from the heat.

Preheat the oven to 170ºC (fan 150ºC). Grease a 25 cm round pie dish.

Make the walnut cake base. Place the walnuts in a food processor. Add 2 tbsp of the flour and blend until the walnuts are finely ground. Add the remaining flour, baking powder, and salt and pulse to combine. Add the cubed butter, sugar, egg yolks, and vanilla and pulse 6-8 times until the mixture comes together. It will be quite a stiff batter. Scoop into the prepared dish and press evenly to cover the base. Pre-bake in the oven for 10 minutes until lightly golden.

Meanwhile, make the meringue. Place the egg whites into a stand mixer (or use handheld beaters) and whisk on a medium speed until soft peaks form, about 5 minutes. With the mixer running add 1 tablespoon of sugar at a time, mixing until the meringue is thick and glossy.

Dollop the blackberry compote over the pre-baked base and carefully spread it out to the sides. Spoon over the meringue smoothing off the surface. Return the dish to the oven and bake for a further 15-20 minutes until the meringue is set and nicely golden.

Cool a little then serve warm.