Preheat your oven to 180°C (350°F). In a mixing bowl, combine the ground biscuits and pistachios, then blend in the melted butter until fully incorporated. Transfer this mixture into an 18cm round pan, pressing down to create an even layer. Bake for about 12.5 minutes, or until the base is set and lightly golden. Remove and cool completely.

Bloom the gelatin leaves in cold water for about 5 minutes. Heat the milk with half the caster sugar until it reaches a gentle boil. Whisk the remaining sugar with egg yolks until thick and pale. Gradually add hot milk to the egg mixture, stirring, then return to the saucepan. Cook until it coats the back of a spoon (about 82°C or 180°F). Stir in softened gelatin and raspberry puree until smooth.

Allow the raspberry mixture to cool slightly before folding in the whipped cream. Pour the raspberry bavarois over the cooled cake base, spreading evenly. Refrigerate for at least 4 hours or until set.

Heat milk with pistachio paste just below simmering. Whisk egg yolks and sugar until pale and airy. Slowly pour hot milk into yolks while whisking, return to saucepan and cook until it coats the back of a spoon (around 82°C). Stir in bloomed gelatin until dissolved and set aside to cool.

Once the pistachio mixture is cool but fluid, fold in the whipped cream gently. Pour this over the set raspberry layer in the cake pan and smooth the top. Refrigerate for another 4 hours or overnight.

Before serving, remove the cake from the springform pan. Decorate with ground pistachios and fresh raspberries. Serve chilled.