Passionfruit-white chocolate semifreddo sandwiches

1.For passionfruit semifreddo, whisk yolks in an electric mixer until pale and fluffy (5-7 minutes). Meanwhile, simmer passionfruit juice and sugar in a small saucepan over medium-high heat, stirring to dissolve sugar, until syrupy (4-5 minutes). Whisking continuously, add syrup to yolks in a thin steady stream, and whisk until cooled to room temperature (8-10 minutes). Whisk cream until soft peaks forms, fold in melted chocolate, then fold in passionfruit mixture. Spread into a 25cm x 34cm tray lined with baking paper and freeze until firm (overnight).

2.Meanwhile, for wattleseed biscuits, preheat oven to 180°C and line several baking trays with baking paper. Beat butter, brown sugar and caster sugar in an electric mixer until light and fluffy (4-5 minutes). Beat in eggs, then stir in flour, milk, nuts, baking powder, wattleseed and a pinch of salt. Refrigerate until firm (1 hour), then roll heaped tablespoonfuls of the dough into balls. Roll each ball in icing sugar to coat thickly, place on baking trays and flatten with the palm of your hand, leaving 5cm between each for biscuits to spread. Bake, swapping trays halfway through cooking, until light golden (10-15 minutes), cool on trays for 10 minutes, then transfer to wire racks to cool completely. Store in an airtight container for up to a week.

3.Cut out rounds of semifreddo with a cutter the same size as biscuits (about 8cm diameter) and sandwich between biscuits, then roll sides in chocolate or macadamia or leave plain and freeze on a tray until firm (1-2 hours). Store in an airtight container for up to 2 weeks.