Line and grease base and sides of a 20cm round cake pan. Preheat oven at 190°C. Whisk eggs, sugar and essence until pale and thick. Sift in flour and fold in quickly using a metal spoon. Stir in corn oil and milk to combine.
Turn batter into a prepared cake pan and bake for 15 minutes or until lightly golden brown. Leave to cool in the pan for 2-3 minutes before turning out to cool completely.