01 - Whisk egg yolks and sugar in a heatproof bowl over simmering water until pale and thickened, 3–4 minutes. Remove from heat and let cool slightly.
02 - Fold mascarpone cheese and vanilla into cooled yolk mixture until smooth. Whip cold heavy cream to stiff peaks and gently fold into mascarpone mixture until just combined.
03 - Combine espresso and coffee liqueur in a shallow dish. Quickly dip each ladyfinger 1–2 seconds per side—do not soak.
04 - Arrange single layer of dipped ladyfingers in 9 x 9 inch dish. Spread half the mascarpone cream evenly over top.
05 - Add second layer of dipped ladyfingers. Top with remaining mascarpone cream and smooth surface evenly.
06 - Cover and refrigerate minimum 4 hours, preferably overnight, to allow flavors to meld and texture to set.
07 - Dust generously with unsweetened cocoa powder and add dark chocolate shavings if desired. Serve chilled.