Step 1

Heat the oven to 180°C/160°C fan/gas Grease the tins, then line with baking paper.

Step 2

Cream the butter and sugar with an electric mixer. Beat in the eggs, one at a time, ensuring each one is incorporated before adding the next. Add the flour, baking powder, cardamom and milk, then whisk for 1 minute. Fold in the 50g pistachios and white chocolate chips, then fill the tins with the batter. Bake for 30 minutes until a skewer pushed into the centre comes out clean. Cool in the tins.

Step 3

For the icing, put the white chocolate in a heatproof bowl and set it over a pan of just steaming water until melted, ensuring the bowl does not touch the water. Set aside to cool slightly. Cream the butter with an electric mixer, then beat in the melted chocolate and vanilla until light and creamy.

Step 4

Remove the cooled sponges from the tins. Spread half the icing on 1 sponge, top with the second, then spread the rest of the icing on top. Sprinkle with the remaining pistachios, then leave for 20 minutes before slicing.