Preheat oven to 160°C. Spray two round 18cm non-stick ring pans with oil
Use an electric beater to beat the sugar, butter and lemon rind in a bowl until light and creamy. Add the egg yolks, 1 at a time. Fold in yoghurt, milk, almond meal and flour until combined.
Beat the egg whites in a bowl until soft peaks form. Fold 1/4 of the egg white into the cake mixture. Fold in remaining egg white. Divide the mixture among the pans and bake for 30 minutes or until a skewer inserted into the centres comes out clean. Set aside for 5 minutes to cool slightly before turning onto a wire rack to cool completely.
To make the icing, stir the sugar, yoghurt and lime juice in a bowl until smooth. Place 1 cake on a cake stand and spoon over the lemon butter. Top with remaining cake. Drizzle over the icing and top with pistachio and lime zest.
* The live active cultures in Vaalia don’t like heat, so serve with Vaalia straight from the fridge for the full benefit of the active probiotic cultures.