1	Whisk egg yolks in an electric mixer until pale and fluffy (5-7 minutes). Meanwhile, stir sugar, passionfruit juice and vanilla seeds in a small saucepan over medium-high heat until sugar dissolves, then simmer until syrupy (4-5 minutes) and add to egg yolks with lime juice, whisking continuously until mixture is cold (5-6 minutes).
2	Combine creams in a bowl, whisk until soft peaks form. Fold into passionfruit mixture, fold in pulp, spoon into an 8cm x 22cm plastic-lined rectangular cake tin, smoothing top (there may be mixture left over), freeze overnight until firm. Slice thickly and serve with extra pulp spooned over.

Note To extract passionfruit juice, process pulp in a food processor, then strain through a sieve (discard solids). Eighteen passionfruit yield about 250ml juice.