Make two cups of coffee and let them cool. Add the vinegar to the milk to sour it. In a very large mixing bowl, sift together flour, soda, salt, baking powder and cocoa. Beat the eggs. Add the beaten eggs, sugar, cold coffee, soured milk, oil and essence to the flour mixture and mix. Beat everything until smooth and runny. Bake at 150º for about 45 minutes ( or until a skewer poked into the centre comes out clean). Make chocolate icing or leave uniced.
Notes
This is a great sharing cake as it can be cut in quarters and given away. Much enjoyed!