Whisk the whites (with a pinch of salt) until they form stiff peaks.
Whisk the yolks with the sugar until they become lighter in colour and thicken (this way, the sugar will act as a natural preservative for the yolks).
Add the whisked yolks to the mascarpone and mix thoroughly.
Fold in the stiff whites with a spatula using gentle figure of eight movements. Set aside in the fridge.
Prepare the coffee and leave it to cool down. Add two or three tablespoons of the chosen liqueur.
The dessert can be assembled on a flat surface (as in the photograph) or in a dish, of the Pyrex type. Arrange a layer of sponge fingers, lightly wetted on one side. On this first layer, the upper side is better. Place a layer of mascarpone cream over this. Repeat the layers and finish with the mascarpone cream.
Leave to rest in the fridge for at least three hours.
Sprinkle with the cocoa powder before serving.
- Advice -
a)We can pasteurise the whites with 50 g sugar and with the help of the microwave: whisk the whites with the sugar for 1 minute and place in the microwave for another minute at medium power (400W), whisk outside the microwave for 2 minutes and again place in the microwave for 1 more minute; repeat the process while the whites are whisked (1 minute in the microwave per white and with intervals outside, being whisked).
b) To have the coffee strength of your liking while still using the correct amount of liquid, you can use freeze-dried or decaffeinated coffee.
c) The traditional tiramisu recipe does not use liqueur. If you wish, you can add any liqueur you like, bitter or sweet tasting.