Preheat oven to 180°C. Grease and line a 20cm round cake tin with baking paper. Set aside.
Melt the butter.
Place the sugar, eggs, milk, orange juice, sifted flour and zest in a large mixing bowl. Add the melted butter.
Using an electric mixer or by hand, mix well for several minutes until smooth and combined.
Scrape mixture into the prepared tin. Bake for 30-40 minutes.
Remove from the oven when a skewer inserted into the cake comes out clean.
Ice with orange icing or top with orange syrup or candied peel. I simply dusted my cake generously with icing sugar and added some fresh mandarin segments.