Pre-heat the oven to 180ºC/160ºC fan/Gas Mark 4 and grease and line 3 x 7 inch loose bottomed cake tins.

In a bowl, whisk together the flour, baking powder, and baking soda, then set aside.

Using a mixer on medium speed, beat the butter and sugar together for about 2 minutes until light and fluffy.

Add the eggs, sour cream, milk, vanilla extract, pistachio cream and half of the flour mix then beat for another minute until well combined. Make sure to scrape down the sides of the bowl as needed.

Finally, add the remaining flour and the pistachio mixture, stirring until everything is fully incorporated. If you're using food colouring, add it now and mix until the colour is evenly distributed.

Divide the batter evenly between the three pans. Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted into the centre of the cake comes out clean. After 10 minutes, take out the tin and allow to cool fully on a wire rack. 

Pop the softened butter into your stand mixer bowl, and beat for around 5-10 minutes, until very pale and fluffy.

 Add in the icing sugar, pistachio cream and vanilla and beat again on a low speed. Scrape down the bottom and sides of the bowl using a spatula. Increase to a medium speed and mix for another 3-4 minutes. 

Once the cakes have fully cooled, level the tops by slicing off any domed parts.
 

Pipe a small amount of buttercream onto your cake board and place the first sponge layer on top to secure it. Pipe a buttercream border around the edge of the sponge.

Spoon the 1/2 the jam in the centre, and spread it evenly in the centre, ensuring it stays within the buttercream border to prevent spillage. Place the next sponge layer on top and repeat the process.

Pipe buttercream around the entire cake and use a palette knife to spread it evenly. Smooth the buttercream using a cake scraper, working from the outside in for a clean finish. Remove any excess buttercream with the palette knife. Chill the cake in the fridge or freezer for 30 minutes to 1 hour to allow the crumb coat to set.

Once the cake is firm, apply the final layer of buttercream, spreading it evenly over the entire cake. Use a warm palette knife or cake scraper to smooth out the edges.

Pipe swirls of buttercream on the top of the cake, and decorate with the chopped pistachios and fresh raspberries.