Whisk egg yolks and icing sugar in a large bowl with an electric whisk on medium / high speed. Whisk 2-3 minutes until it gets a white / light yellow color and creamy texture (the color depends on how colorful the egg yolks are).

Add mascarpone and mix until it becomes smooth and creamy. Whisk for 2-3 minutes.

Quickly dip both sides of the savoiardi biscuits in coffee and place in the bottom of a pan. Dipping the biscuits quickly is very important so they don't absorb too much coffee, which can make the cake watery.

Spread a third of the mascarpone cream over the biscuits.

Make two more layers with biscuits and mascarpone cream (there should be 3 layers where the last one has cream on top).

Wrap the pan tightly with plastic wrap so no air and smells from the fridge enter the tiramisu.

Refrigerate for at least 4 hours, but preferably overnight.

Powder the dessert with cocoa before serving.