1. Heat oven to 170. Grease and line 4 x 20cm cake tins and set aside.
2. Process the pistachio nuts in a blender then add the flours, baking powder salt and bicarb soda
3. Whisk the butter and sugar until light and fluffy. Add the sour cream. Fold in the dry nix gently with the pistachio milk.
4. Whip the egg whites with a pinch of salt until soft peak. Fold into the cake batter and divide evenly amongst the cake pans.
5. Place in the oven and bake 12-15 minutes until the centre springs back to the touch. Remove and allow to cool completely.
6. To make the Pistachio cream, combine egg yolks, sugar, cornflour to a smooth paste. Add 60ml of pistachio milk.
7. Heat the remaining 300ml of pistachio milk. When hot slowly whisk in the egg mix. Keep whisking over medium heat until it thickens. Pour into a bowl or container and allow to cool completely. (overnight)
8. Whip pistachio cream with a whisk until light. If you would like to make this cream lighter add a little whipped cream or whipped coconut cream if you prefer this to be dairy free.

To assemble the cake

1. Extra chopped pistachio nuts
2. Dried rose petals
3. Place a cake layer on a serving platter. Pipe or spread a layer of pistachio cream on top. Repeat with each layer. Sprinkle with chopped pistachio nuts and dried rose petals