1. Separate the egg yolk and white, whisk the egg yolk and sugar until fluffy and then add the mascarpone and whisk for few minutes.
2. Beat the egg whites until firm and stiff, fold the egg whites into the mascarpone mixture.
3. In a serving dish arrange the butter biscuits in the bottom, pour some coffee over them and the arrange another layer on top.
4. Next pour the cream on top and spread it evenly, then put a layer of butter biscuit and pour some coffee and finally pour the last layer of mascarpone cream.
5. Sprinkle some dark chocolate powder and keep it in the fridge for couple of hours.
6. Serve the Tiramisu after a nice hearty meal.
Arrange one butter biscuits vertically and the other horizontally as this will leave no gaps for the coffee to steep in the cream.