Put the cocoa in a small bowl, add some of the extra milk and stir until the cocoa powder is all wet. (You need enough milk to make a fairly runny mixture, as the cocoa will absorb more liquid and go thicker as it stands). Put aside until ready to use. Beat the eggs and sugar in a large bowl until light and slightly thick. Add the melted butter and beat again. Stir the cocoa mixture again and add a little more of the extra milk if it has gone too stiff - should be thick and sloppy by the time you add it to the cake mixture.

Fold the flour and milk/cream into the eggs/butter/sugar mixture in alternate batches, adding the cocoa mixture with the last batch of milk/cream, and finishing with a batch of flour. Grease and flour 2 layer cake tins (20-22 cms diameter), divide the cake mixture evenly between the 2 tins, making a slight depression in the centre, and bake at 350° for about 30 minutes. Test with a skewer and if not cooked through, lower the temperature to about 300° and cook for another few minutes or so as needed. The cake will be beautifully moist as long as you don't overcook it. Cool on cake racks before turning out.

Spread the whipped cream between the completely cooled layers. Put the icing sugar, soft butter, cocoa, in a bowl and beat with enough hot water to make a thick, stiffish icing, beating well until smooth and creamy but not at all runny. Add extra icing sugar and/or hot water as needed, to get the correct consistency and amount of icing needed. Spread icing on the cake with a flat knife - do the sides first if you are going to completely cover the cake. If icing goes a bit stiff, it will be easier to spread if you dip the knife blade in very hot water.