Beat butter until light and creamy.
In a separate bowl, whisk eggs and castor sugar until light and
fluffy. Stir in beaten butter and essence. Carefully fold
in sifted ingredients alternately with ice cream soda. Pour
mixture into a 21-cm round cake tin lined with greased greaseproof
paper. Bake in an oven preheated to 175°C for 35-40 minutes or
until cooked when tested with a skewer.