I combined a few different recipes while putting this together
True tiramisu requires an extended rest period of eight to ten hours before serving, because this downtime allows the dry ladyfingers to fully absorb the surrounding moisture without dissolving into mush. Whipping whole eggs and yolks with sugar until the mixture forms a thick ribbon stage incorporates enough air to support the heavy mascarpone cheese without deflating it.
Heavy cream requires distinct mechanical action compared to whole eggs, needing to reach stiff peaks with added sugar and salt before folding into the mascarpone base. Judge this stage visually by lifting the beaters; the cream must hold a rigid, upright peak that does not curl over at the tip. Espresso should be hot when mixing with sugar, but cooled down before dipping the biscuits to prevent the sponge from breaking apart prematurely.