Preheat the oven to 180C. Grease and flour a 24cm cake tin and leave to the side
Sieve the ricotta into a bowl, using a wooden spoon to push it through the sieve. Add to it the eggs yolks, sugar, ground almonds, melted chocolate, orange juice and vanilla seeds and combine.
In a clean bowl (I do it in my kitchen aid) whisk the egg whites until peaks are formed. Using a metal spoon fold the egg white into the ricotta mixture. Combine it slowly, trying to keep it as airy as possible. Put the cake mix into your prepared tin, and smooth on top. Bake for 45 minutes.
Take it from the oven, let it cool, and then transfer to a cake plate. Dust with icing sugar and crushed pistachios.
I serve it with a dollop of orange infused creme fraiche.