Step One: After pre-heating the oven to 180 degrees Celsius, grease a deep 23cm round cake tin and line the base, using grease-proof paper.
Step Two: Break the chocolate into small pieces and slowly melt them over a pan of hot water. Stir the chocolate occasionally, then allow to cool slightly.
Step Three: Beat the butter in a bowl until very soft, then gradually beat in the sugar until the mixture becomes light and fluffy.
Step Four: Add the chocolate and vanilla extract to the butter and sugar mixture, then beat again.
Step Five: Add the egg yolks to the mixture, then fold in the ground almonds and sieved flour.
Step Six: In a separate bowl, whisk the egg whites until stiff. Make sure the egg whites don’t dry out and then add one-third to the chocolate mixture and stir vigorously. Then gently fold in the remaining egg whites.
Step Seven: Pour the mixture into the tin, level out and bake for 50 minutes. The cake should spring back when pressed.
Step Eight: Leave to cool in the tin for a few minutes, then remove from the tin and paper before leaving to cool on a wire rack.
Step Nine: Make the topping by heating apricot jam in a small pan, before brushing evenly over the top and sides of the cooled cake, and allow to set.
Step Ten: Make the icing by heating the cream until piping hot. Remove the cream from the heat and break plain chocolate up, adding into the cream. Stir until the chocolate has melted and then cool. Spread gently over the cake, then leave to cool.
Step Eleven: For the Viennese effect, make a little extra icing and pipe the word ‘Sacher’ across the top of the cake.