Place chocolate and whipping cream in a heatproof bowl and place over a pan with simmering water. Melt over low heat.
Let cool at room temperature until thickens.
Remove the plastic wrap from the log. Cut the ends of the log.
Cut about a 4-inch (10cm) section off one end. Cut the section diagonally on one end.
Place the log and the section onto a serving platter.
Place the small piece with the diagonal cut side against a side of the roll, to form a branch.
Spread the ganache on top and sides of the cake. Leave the cut ends uncovered.
Use a fork to create lines on the ganache.
Sprinkle desiccated coconut.
Decorate the buche de noel with fresh mint or rosemary and sugar-coated cranberries.