Preheat oven to 180°C. Grease and flour the bottom only of 2 20cm dia cake tins.
In a large bowl, beat eggs until appearance is thick and lemony. Beat in sugar and vanilla.
In a medium bowl, sift together the flour, baking powder and salt. Gradually stir flour mixture into egg mixture.
In a saucepan, bring the JUST MILK and butter to a boil. Remove from heat and add all the hot milk mixture to batter mixture. Stir until well combined.
Pour mixture into prepared cake tins, using a spatula to get remaining batter out of bowl, and to spread batter evenly.
Bake for 30-35 minutes or until a toothpick inserted into the centre comes out clean
Cream the butter in a bowl using the back of a wooden spoon. Keep stirring until it's of a creamy consistency. Add 280g of the icing sugar a spoonful at a time, continuing to cream the butter between each spoonful, until all the sugar has been thoroughly mixed in.