Pistachio layer cake with cream cheese frosting

Method

1. Heat the oven to 170°C fan/gas 5 and grease and line the bases of the sandwich tins with butter and baking paper. Put the pistachios in a food processor and whizz to a fine crumb (don’t overwork otherwise they may start to release their oils and become buttery). Tip 260g of the whizzed nuts into a large mixing bowl and set the rest aside for later.
2. Tip the flour into the bowl of pistachios and add a pinch of fine salt. In a jug, lightly beat the eggs with the vanilla extract. In a second bowl, use an electric whisk or stand mixer to beat the butter and sugar together for 8-10 minutes, or until the mixture is very pale and fluffy; almost mousse-like.
3. Continue mixing the butter and sugar on a medium speed while gradually adding the beaten eggs. Once added, gently stir in the flour and whizzed pistachios, followed by the soured cream, using a large metal spoon. Divide the mixture among the sandwich tins as evenly as you can, using a palette knife to smooth the tops and create a slight dip in the centre (which helps create a level sponge). Bake in the centre of the oven, ideally on the same shelf (but without the tins touching) for 19-23 minutes. The cakes are ready when they’re springy to the touch and starting to come away from the edges.
4. Run a palette knife around the edge of each sponge to release them from their tins, then turn upside down onto a wire rack. Peel away the paper and leave to cool completely.
5. Meanwhile, make the icing. Beat the butter with an electric whisk until soft and fluffy. Mix in the cream cheese until there are no lumps (but do not overmix as it will become too runny). Beat in the icing sugar and vanilla until just combined, then cover and chill until ready to use.
6. Once the sponges have cooled, begin layering up the cake on a stand or plate. Use about a quarter of the icing between each sponge, then use the remaining icing to completely cover the top and sides of the cake, using a palette knife. If the cake feels like it’s sliding around a bit, pop it in the fridge for 20 minutes before adding the outer icing. It can also help to spread a very thin layer of icing over the outside of the cake, known as a crumb coat, then chill again before adding the final layer of icing. It helps prevent lots of crumbs getting pulled into the icing and keeps everything more stable.
7. To create a decorative ridge pattern, put the cake on a turntable and hold the palette knife at a right angle to the cake. Lightly press the knife into the icing while you twist the cake, starting at the bottom and moving upwards to create a ribbon effect. Do the same on the top of the cake, starting from the centre. Or just run the palette knife around the cake in a decorative pattern. Sprinkle the remaining pistachios around the top edge of the iced cake.