Make the coffee soak by dissolving the sugar in the hot strong coffee, then allow to cool.
Place the mascarpone, vanilla seeds and icing sugar into a separate bowl and mix together. Fold in the whipped cream.
To assemble, dust the bottom of the four individual glasses or a serving dish with the cocoa powder.
Dip the panettone into the cooled coffee and arrange on the bottom of the dish.
Place half of the mascarpone mixture over, then dust again with the cocoa powder, followed by a soaked panettone layer, mascarpone and finish with a layer of cocoa powder.
Transfer the glasses to the fridge to chill for up to 2 hours.