A classic Italian dessert made with coffee-soaked ladyfingers layered with a rich mascarpone cream and finished with a dusting of cocoa powder.
Whisk the egg yolks and sugar together in a heatproof bowl until pale and slightly thickened.
Place the bowl over a saucepan of gently simmering water, making sure the bottom does not touch the water.
Continue whisking for 5 to 7 minutes, until the mixture becomes thick and reaches a safe temperature.
Remove the bowl from the heat and let the mixture cool slightly.
Add the mascarpone cheese and gently mix until smooth.
In a separate bowl, whip the heavy cream until stiff peaks form.
Fold the whipped cream into the mascarpone mixture in several additions, taking care not to deflate it.
Combine the cooled espresso with the coffee liqueur, if using.
Quickly dip each ladyfinger into the espresso mixture, coating both sides without allowing it to become soggy.
Dip the ladyfingers very quickly so they absorb the coffee without falling apart. Chilling the tiramisù overnight produces the best texture and allows the flavors to fully develop.
Arrange a single layer of dipped ladyfingers in the bottom of a serving dish.
Spread half of the mascarpone mixture evenly over the ladyfingers.
Repeat with another layer of dipped ladyfingers and the remaining mascarpone mixture.
Cover and refrigerate for at least 6 hours, or overnight, to allow the dessert to set.
Dust generously with cocoa powder and garnish with grated dark chocolate before serving, if desired.
