Preheat the oven to 180-200°C.
Melt chocolate and butter in a double boiler over hot water
(Bain Marie, "im Wasserbad"). If you do not have
a double boiler you can also use a normal pan filled with
water and with a smaller pan in it. Remove from heat and let
the mass cool.
Add the powdered sugar and the egg yolks little by little
while carefully stirring.
Beat the egg whites and add the white sugar. Mix into the
batter and add the flour gradually while constantly stirring.
Pour batter into a greased spring form pan. Bake at 165°C
for 50 to 60 minutes.
Allow the cake to cool completely before removing from pan
and before icing.
Once cool remove the cake from pan then slice horizontally.
Insert a filling of pureed jam between the layers.
Melt chocolate and coconut shortening in a double boiler over
hot water and cover the top and sides of the cake with the
warm (not hot) icing.