Beat the yolks with the powdered sugar until whitened and until you get a smooth cream. Add the mascarpone and carefully stir with a stirrer or wooden spoon.
Separately, beat the egg whites to hard snow and then mix them with the rest of the cream.
Add the cognac or rum to the freshly brewed espresso. Prepare suitable dessert bowls, pour chocolate glaze on their bottoms.
Dip the biscotti 1 by 1 briefly in the coffee and arrange them in 1 layer in the individual cups/bowls. Put a layer of cream on top, biscotti again and finish off with cream. You can have just 1 layer of biscotti if you like.
Put the Tiramisu in Cups to sit overnight in the fridge before serving. Before serving, sprinkle generously with sifted cocoa.
*Instead of biscotti, you can use ladyfingers.