Steps
1. In a bowl, combine the chopped dark chocolate and sugar. Melt them together over a double boiler until smooth and glossy.
2. Whisk the egg yolk into the melted chocolate mixture until well incorporated.
3. In another bowl, whip the heavy cream with the vanilla extract until soft peaks form. Gently fold the whipped cream into the chocolate mixture until fully combined.
4. Quickly dip each champagne biscuit into the cooled coffee, ensuring they are soaked but not soggy.
5. In a glass dish, start layering: place a layer of soaked biscuits, followed by a layer of the chocolate cream. Repeat until you reach the top, ending with a layer of chocolate cream.
6. Chill in the refrigerator for at least 2 hours to set.
7. Before serving, dust the top with cocoa powder and garnish with chocolate shavings. Serve with a spoon and enjoy!