Place the biscuits in the bowl of a food processor and process until they resemble fine breadcrumbs. Add the butter and mix to combine. Press the mixture into the base of a 20x30cm lightly greased rectangular tin lined with baking paper. Refrigerate for 30 minutes or until firm and cold.
Preheat the oven to 160ºC (320ºF). Place the ricotta, cream cheese, caster sugar and lemon rind in the bowl of a food processor and process until smooth. Gradually add the eggs, processing well after each addition. Fold through the passionfruit pulp and pour the mixture over the base. Bake for 25–30 minutes or until set. Allow to cool completely. Slice to serve. Serves 8.