Rainbow Cake - Blue Crystal Sugar

Ingredients

• 4 extra large eggs
• 260 g (1 ¼ cup) Huletts Castor sugar
• 300 g (550 ml) cake flour
• 15 ml (1 T) baking powder
• 1 ml (pinch) of salt
• 250 ml (1 cup) milk
• 100 g butter
• 5 ml (1 t) vanilla essence
• a variety of food colouring
• 1 kg butter
• 1 kg (4 cups) Huletts Icing Sugar