Pre-heat oven to 180°C. Grease and line a 28cm cake tin.
Beat the butter and sugar until pale and creamy (approximately 3-4 minutes). Add the egg yolks and beat until combined and creamy. Add the flour, baking powder and milk and beat on low until combined. Next, add the chocolate and spices and mix well. Finally, beat the egg whites until they form firm peaks and carefully fold into the dough until just combined.
Pour into the cake tin and bake for 50-60 minutes or until a wooden skewer inserted into the middle comes out clean.
Cool for 10 minutes in the cake tin and then turn onto a wire rack.
Mix the icing sugar with the rum and cream until smooth and pour over the completely cooled cake.
