Curd

In a saucepan over medium heat, add lime zest and juice, passionfruit pulp, sugar, butter and cornflour. Whisk until butter is melted then continue whisking while slowly adding the egg. Gently cook, stirring constantly, for 4–5 minutes, until mixture thickens.
Remove curd from heat and allow to cool a little before refrigerating until ready to use (once cake has completely cooled).
(Makes 1 cup.)

Cake

Meanwhile, preheat oven to 180°C. Grease a 20cm x 20cm baking tin then line with baking paper.
In a mixing bowl, add butter and sugar and beat until pale. Add mascarpone and continue to beat until fully incorporated. Slowly stir in egg then add sifted flour, baking powder and salt and fold together gently.
Pour mixture into prepared tin then bake for 25-30 minutes, until a skewer inserted into the middle comes out clean. Remove cake from oven.
In a jug, combine lemonade and rum then pour it over the cake. Remove cake from tin and place on a wire rack to cool.

To finish

When cake has completely cooled, in a bowl add curd and mascarpone and mix well to combine.
Spread curd and mascarpone mixture over the top and sides of the cake, sprinkle with chopped pecans and serve.