Rhubarb and pistachio syrup cake

Method

1. Put 215g of the caster sugar, the lemon zest, juice and 200ml water in a small saucepan over a medium heat. Stir until the sugar dissolves, then increase the heat to high and bring to the boil. Reduce the heat to low-medium and simmer for 2 minutes or until the syrup thickens. Stir in half the rhubarb, then set aside to cool.
2. Heat the oven to 160°C fan/gas 4. Grease and line the bottom and sides of the springform tin. Whizz the pistachios in a food processor until finely ground. Sift the flour, semolina and baking powder into a large bowl, then stir in the ground pistachios.
3. In a separate bowl, use an electric mixer to beat the butter and remaining 155g sugar until pale and creamy. Add the eggs, 1 at a time, beating well after each addition. Fold in the flour mixture and yogurt until fully incorporated, then add the remaining rhubarb pieces. Spoon the cake mixture into the prepared tin and smooth the top. Bake in the oven for 1 hour or until a skewer pushed into the centre comes out clean.
4. While the cake is still warm, use the skewer to pierce holes all over the surface. Pour the rhubarb syrup over the cake, reserving the soaked rhubarb. Set aside to cool in the tin. Transfer the cake to a serving plate and top with the reserved rhubarb and any remaining syrup. Sprinkle with extra chopped pistachios to serve.