Scoop the pulp and flesh from the passionfruit halves into a sieve sat over a bowl. Press the pulp through the sieve then discard half of the seeds. Add half of the icing sugar to the passionfruit pulp/juice and stir to mix well. Soak the savoiardi fingers in the passionfruit juice and arrange 4 evenly spaced apart in each serving glass.
Whip the cream with the rest of the icing sugar in a large mixing bowl until soft peaks form. Fold the passionfruit juice/purée and the seeds in the cream. Transfer to a piping bag fitted with a star-shaped nozzle.
Pipe the cream into the centre space of the glasses.