Cake

1. Preheat oven to 356°F (180°C). Line the base and sides of a 20cm round cake tin with baking paper.
2. Place 100g of castor sugar and the lemon zest in a food processor and blitz until finely ground.
3. Beat the butter, vanilla, and sugar/zest mixture together for about 10 minutes until pale and creamy.
4. Add the egg yolks one at a time, beating the mixture well after each addition.
5. Add the almond meal and beat to combine. Fold in the ricotta.
6. Beat the egg whites in a clean bowl until soft peaks form.
7. Gradually add the remaining sugar to the egg whites and whisk until stiff peaks have formed.
8. Mix a third of the egg whites into the cake mixture, then gently fold in the rest of the egg white mixture.
9. Pour the mixture into the prepared cake tin and smooth the top.
10. Bake for 40-45 minutes at 356°F (180°C), until cooked and firm to the touch.
11. Allow to cool completely in the cake tin before removing.

Pistachio Frosting

1. Preheat oven to 392°F (200°C) and toast the pistachios on a baking sheet for 5-7 minutes until fragrant.
2. Let the pistachios cool, then pulse in a food processor to a mix of coarse and fine textures.
3. Beat the butter and icing sugar until fluffy; add the cream cheese, vanilla extract, lemon zest, and salt, and beat until smooth.
4. Stir in about 1 3/4 oz (50 g) of the toasted pistachios. Spread the frosting over the cooled cake and sprinkle with the remaining pistachios.