Preheat the oven to 160ºC (320ºF). To make the passionfruit syrup, place passionfruit pulp, water and sugar in a small saucepan over medium heat and stir until sugar is dissolved. Bring to the boil, reduce the heat to low and cook for 10–15 minutes or until syrupy. Set aside.
Place the butter, sugar and vanilla in the bowl of an electric mixer and beat for 10–15 minutes or until pale and creamy. Add the eggs, one at a time, beating well after each addition. Add yoghurt and beat until well combined. Fold through flour. Spoon mixture into a lightly greased 24cm bundt tin+ and bake for 35 minutes or until cooked when tested with a skewer. Remove cake from the tin and place on a serving plate. Spike all over with a thin skewer, drizzle cake with syrup and serve while still warm. Serves 8.
+ A bundt tin is a round, fluted cake tin with a hole in the centre.