Authentic Tiramisu

(2-2½ cups) strong espresso, cooled to room temperature

large eggs or 5 small/medium eggs, separated

sugar (one tablespoon per egg) I use a regular spoon to measure - if you use a measuring spoon it will taste sweeter (personal preference).

mascarpone cheese, room temperature

200-250 g (7-9 oz) pkg Savoiardi or Pavesini (lady fingers) These are known as Löffelbiscuits in Germany.

unsweetened cocoa powder (or to taste) Again, I use a regular spoon but a measuring spoon will also work.