Preheat oven to 150°C fanbake and line an oven tray with baking paper.

Beat butter, sugar and vanilla until pale and creamy.

Sift in flour and custard powder and mix to form a very soft dough – initially it will look crumbly but when you press it together it should form a soft, smooth dough.

Roll dessertspoon-sized scoops of dough into small balls, arrange on prepared tray, and flatten gently with your palm and then with a fork.

Bake until set and very lightly golden (about 25 minutes).

Allow to cool on the tray for 5 minutes, then transfer to a rack to cool completely.

While cookies are cooling, make Passionfruit Honey Buttercream.

Beat butter until light and fluffy.

Add icing sugar, ½ cup at a time, beating between additions.

Beat in passionfruit pulp and honey, adding a little extra passionfruit pulp if necessary until the desired consistency is achieved.

Beat for 3-5 minutes for an extra light fluffy icing.

When cookies are cold, spread 1 tablespoon Passionfruit Honey Buttercream on the flat side of half of them and sandwich another cookie on top of each.

Drizzle a little passionfruit syrup or pulp over the icing, if desired.

Store in an airtight container for up to 1 week.