Clean mushrooms and remove any hard parts.
Cut mushrooms into small pieces.
Add mushrooms together with chocolate, milk, sugar, and coconut block to a pot.
Cook on a very low heat until the chocolate and coconut block melt. Stir constantly.
Transfer the mixture to a blender and blend until smooth.
Brush the form with coconut oil.
Transfer the mixture into the form.
Decorate the cake with, for example, coconut flakes. Place the form in the fridge for 5 hours, or overnight. When the cake cools down and the mixture stabilizes, remove the cake from the form.