1. COMBINE water, sugar, butter, cocoa and bicarbonate soda in a saucepan and warm, but do not boil, stirring until the sugar has dissolved and the butter has melted. Transfer mixture to a bowl and cool for 30 minutes. Beat in the eggs and vanilla. Stir in the flour and mix well. Pour into a greased and base-lined 20cm round cake pan.
2. BAKE in a moderate oven 180°C for 50 minutes or until cooked. Cool for 10 minutes before turning onto a wire rack to cool completely.
3. PLACE the cream in a saucepan and just bring to a boil. Pour over the chocolate and whisk vigorously to combine. Set aside to firm for up to 2 hours at room temperature. Maybe stored, covered, in the refrigerator until required, but will require time standing to soften before using.
4. SPREAD the cooled cake with the ganache. Serve immediately.
NB: To achieve a layered cake, cut cake in half once cooled. Double the recipe for the icing, once set spread generously between the layers. Decorate with chocolate curls and lattice shapes to add a special touch.