Prepare all the ingredients.

Finely crush the chocolate coating...

...and melt it in a bain-marie or oven or micro-wave.

When melted, add the strong coffee...

...then mix to smoothen.

Separate the egg whites.

cremer the yolks with sugar.

Add melted chocolate.

Mix well.

Beat the egg whites very firm with a pinch of salt.

Add these whites to the chocolate preparation...

...and delicately incorporate them using a rubber spatula...

...until you obtain an homogeneous preparation.

Pour this preparation in a génoise mold that was previousely lined with greased parchment paper.

Bake 12 to 15 minutes at 180°C.

When finished...

...remove from the mold on a tea towel and leave to cool.

Whip the very cold single cream into whipped cream.

Add icing sugar and rum.

Remove the sheet of parchment paper stuck to the biscuit.

Pour the whipped cream on the chocolate biscuit...

...and spread all over the surface.

Roll the biscuit from one side.

Help yourself using the tea towel to lift it.

Once rolled up...

...trim the ends diagonally.

Sprinkle the whole surface...

...with cocoa.

Dress on a serving dish or cake box and decorate with Christmas figurines. Reserve in the fridge until serving.