1) In a saucepan bring the water and caster sugar to the boil.
Remove from the heat and add the lemon zest and mint leaves. Leave to rest in infusion for 30 minutes, then filter the mixture.
2) Base: finely crush the Zuppole Balocco biscuits, then add in the cool, melted butter and the liqueur. Cover the base of the mould with greaseproof paper, then pour in the biscuit mixture. Press well onto the base while levelling off the surface and place in the fridge.
3) Filling: whip the ricotta with the icing sugar, then gradually pour in the infusion. Heat the liqueur and melt in the isinglass already soaked in cold water and well-squeezed. Add the liqueur to the ricotta and complete the mixture with the whipped cream. Mix, pour the mixture into the mould, level it off and place in the fridge until ready to serve.
4) Decoration: just before serving, turn out the cake onto the serving dish, then decorate it with fruit and mint leaves.
An extra tip:
If you like monochrome decorations, opt for red and decorate the cake with a crown of redcurrants, strawberries and raspberries.