Place Ricotta in a sieve over a bowl for a few minutes to drain
Place Ricotta and sugar in a large bowl and mix well
Add egg yolks and vanilla and mix until smooth. Stir in cream
Whip egg whites in a separate bowl until stiff peaks form. Fold gently into Ricotta mixture along with raisins, lemon and orange rind
Grease a 20 cm round springform cake pan with butter and sprinkle with biscuit crumbs. Pour filling into tin and smooth surface with a spatula
Place in oven and bake for 10 minutes, then reduce heat to 180°C and continue to cook for another 55 minutes, or until the cake is nicely browned on top and just set
Turn off oven with the oven door ajar and leave cake to cool completely in oven, if possible
Dust with icing sugar and decorate with fresh cherries or berries and a dollop of mascarpone