Beat softened butter, sugar, vanilla sugar, and salt in a separate bowl.
Gradually add the eggs, then sour cream and grated coconut. Beat again.
Mix the flour with baking powder and add to the mixture.
Melt chocolate with cream.
Add the melted chocolate to 1/3 of the dough and beat until smooth.
Grease a 22 cm diameter baking mold, pour a bit of white dough, then all the chocolate layer, and finally the remaining white dough. Level the surface.
Bake for 60-70 minutes at 170°C. Remove from the oven and let cool.
Beat chocolate with cream, gradually adding the cream to obtain a moderately thick consistency. Cover the cake with this mixture and sprinkle with grated coconut.
The muffin turns out very delicious and delicate, perfect with a cup of tea or coffee.