Place the egg yolks in a mixing bowl and whisk with half the sugar until frothy and light in color.
In another large mixing bowl, whisk the egg whites until they form bubbles. At this point, add the remaining sugar and continue beating until the egg whites are stiff.
Drain the mascarpone. Using a spatula, carefully fold in the egg yolk and sugar mixture and then gradually fold in the stiff egg whites. Place the cream in the fridge for at least an hour.
Cut the panettone into three pieces with two slices. Mix the vin santo with the coffee and drizzle lightly over each piece of panettone. Caution: only drizzle lightly, do not soak the cake.
Chop the chocolate into small pieces with a large knife
Spread half of the cream and a third of the chocolate on the base of the panettone. Now carefully place the middle piece on top, spread with the other half of the cream and sprinkle with another third of the chocolate sprinkles. Finally, place the lid on top.
Place the filled cake in the fridge for at least 30 minutes. Before serving, sprinkle with powdered sugar and decorate with the rest of the grated dark chocolate.