1.Preheat oven to 180°C. Grease eight holes of a 12-hole muffin pan.
2.Combine flour in a medium bowl with ¼ cup of the sugar and all the grated rind. Add egg, butter, milk and yoghurt; stir until just combined. Divide mixture among pan holes and bake about 25 minutes. Stand cakes in pan 5 minutes before turning, top-side up, onto a wire rack.
3.Meanwhile, combine the water and remaining sugar in a small saucepan. Stir over heat until sugar dissolves; bring to the boil. Reduce heat; simmer, uncovered, without stirring, 10 minutes. Stir in blended cornflour and passionfruit until mixture boils and thickens. Strain into a small heatproof jug; reserve some of the seeds.
4.Stir sliced rind and reserved seeds into syrup; cool. Serve lemon cakes with passionfruit syrup. Dust with icing sugar, if you like.
You will need about six passionfruit to make this recipe. The thin-skinned purple-black variety will yield much more pulp than the thicker-skinned Panama passionfruit.Note