Preheat the oven to 180°C and grease/line two 20cm sandwich tins.
Beat all cake ingredients except boiling water in a bowl until smooth.
Gradually stir in the boiling water until the mixture is smooth and liquid.
Divide batter between tins and bake for 25-35 minutes until firm.
Allow cakes to cool completely in their tins before removing.
Melt chocolate and cream over low heat then whisk until glossy.
Cool the icing for 1-2 hours until thick enough to spread.
Remove cakes from tins and sandwich together with a layer of icing.
Cover the entire cake with the remaining chocolate icing using a palette knife.