This is assembly rather than baking: dry sponge fingers absorb coffee and become soft layers between cream. The classic tiramisu failure is a soggy mush at the bottom, caused by dipping too long, not by the cream.
Ingredients and what each one does
- Ladyfingers (savoiardi) are dry and porous, which is why they absorb liquid like a sponge. Homemade ones from whisked eggs work the same way.
- Coffee, strong and cooled. It gives flavour and moisture. Hot coffee collapses the biscuit in a second.
- Alcohol (rum, liqueur) is optional. It is also liquid, so do not increase the total amount of soaking liquid.
How to make it
- Brew strong coffee (espresso or similar) and cool it to room temperature fully. In hot coffee the biscuit goes to paste instantly.
- Add a little sugar if the coffee is bitter, and alcohol if you use it.
- Dip each finger for 1 to 2 seconds per side. Sign: when you snap one, the centre is still dry. It will keep absorbing moisture from the cream in the fridge.
- Lay them tightly in one layer without gaps. Fill any gaps with broken pieces.
- Cover with cream straight away. Soaked biscuit left uncovered turns soggy quickly.
What can go wrong
- Mush at the bottom. The fingers were dipped too long or the coffee was hot. Cut the dip time, not the amount of coffee.
- Dry layer. The biscuit did not take enough. Give the cake at least 6 hours in the fridge, so moisture redistributes.
- Coffee leaking out of the sides. Soaked biscuits were squashed. Just press the layer flat with your palm.
Substitutions
Dry sponge cake cut into strips can replace ladyfingers. Soft sponge does not work, it absorbs too little and falls apart.
Storage
Only inside the assembled dessert, in the fridge for up to 2 days. Soaked biscuits are not stored on their own.