Preheat the oven to 160ºC (320ºF). To make the passionfruit filling, place the butter and icing sugar in the bowl of an electric mixer and beat for 6–8 minutes or until pale and creamy. Strain the passionfruit through a sieve to remove the seeds. Add to the butter mixture and beat for a further 3–4 minutes or until smooth. Set aside.
Place the butter, icing sugar and lemon rind in the bowl of an electric mixer and beat for 6–8 minutes or until pale and creamy. Add the flour, cornflour and passionfruit pulp and mix until combined. Roll 2 teaspoonfuls of the mixture into balls with damp hands and place on baking trays lined with non-stick baking paper. Press each biscuit with a damp fork to flatten. Bake for 12–15 minutes or until light golden. Allow to cool on trays. Sandwich the biscuits together with the passionfruit filling to serve. Makes 16.
Note: If the biscuit mixture gets a little sticky to roll, refrigerate it for 15–20 minutes and then start rolling again. Having slightly damp hands will prevent the mixture from sticking when rolling.