Preheat oven to 180c.

Place the butter, lime zest and sugar in a bowl and beat until pale and creamy.

Add the egg yolks, one at a time, beating well after each addition.

Fold through the flour then gradually add the milk in a steady stream whisking lightly to combine.

Add the lime juice and mix to combine. The mixtue will look slightly curdled.

Whist the egg whites until stiff peak form. Using a large metal spoon, fold lightly through the batter.

Pour batter into 4 x 1 cup ramekins and bake for 15 minutes or until lightly browned.

Place a dollop of yoghyrt and a teaspoon of passionfruit pulp on top to serve.