Preheat oven to 180°C/160°C fan-forced. Grease a 22cm fluted ring pan.

Strain passionfruit pulp over a small jug (you'll need 1/2 cup juice and 2 tablespoons passionfruit seeds).

Place butter, lemon rind, sugar, eggs, passionfruit juice, milk and flour in a bowl. Using an electric mixer, beat on low speed until combined. Increase speed to high. Beat for 2 to 3 minutes or until pale. Stir in passionfruit seeds. Spread mixture into prepared pan. Bake for 50 minutes or until a skewer inserted in the centre comes out clean. Stand in pan for 10 minutes. Turn out on to a wire rack to cool.

Make glace icing: Combine icing sugar, lemon juice and butter in a small bowl. Stir with a wooden spoon until a spreadable consistency. Spread over cake. Top with lemon rind. Serve