120 grams (1 stick) unsalted butter, softened
275 grams (1 1/3 cups) caster sugar
1 vanilla bean, split and seeds scraped
1/4 cup lemon zest
4 eggs, separated and at room temperature
240 grams (2 1/2 cups) almond meal
300 grams (10 1/2 oz) ricotta
Flaked almonds, to decorated
Icing sugar, for dusting
Heat oven to 160 degree celcius fan-force (325 degree fahrenheit fan-forced). Line the base and sides of a 20cm round cake tin with baking paper and set aside.
Place the butter, 165 grams caster sugar, vanilla seeds and lemon zest in an electric mixer and beat for 8-10 minutes or until pale and creamy. Scrap down the sides of the bowl, then gradually add the egg yolks, one at a time, continuing to beat until fully combined. Add the almond meal and beat to combine. Fold ricotta through the almond meal mixture.
Beat the egg whites in a clean bowl with a hand-held electric mixer until soft peaks form. Gradually add the remaining sugar to the egg whites mixture and whisk until stiff peaks form. Gently fold a third of the egg whites into the cake mixture. Repeat with the rest of the egg whites.
Pour the mixture into the prepared cake tin, smooth the tops with a palette knife, decorate the cake with almond flakes, and bake for 40-45 minutes or until cooked and firm to touch. Allow to cool completely in the cake tin. Dust with icing sugar to serve.