Mix together the flour, sugar,
bicarbonate of soda and salt. Rub in the butter or margarine until the
mixture resembles breadcrumbs, then beat in the buttermilk, eggs and
cocoa and continue to beat until smooth. Spoon the mixture into two
greased and lined 23 cm/9 in sandwich tins (pans) and bake in a
preheated oven at 180°C/350°F/gas mark 4 for 30 minutes until a skewer
inserted in the centre comes out clean. Sandwich together with half
the American Velvet Frosting and cover the cake with the remainder.
Leave to set.