Tiramisu

Whisk egg yolks and sugar in a metal bowl until well-combined. Set over a pot of simmering water (water should not touch the bowl) and continue to whisk until lightened and thickened.

Whisk mascarpone into custard until smooth. Let cool, then chill until cold and firm.

Whip cream with vanilla until it forms stiff peaks. Fold cream into the mascarpone mixture.

In a flat-bottomed bowl or baking dish, stir the cognac or rum into the coffee. Dip lady fingers into the coffee mixture, no more than 2 seconds per side, and arrange closely on the bottom of a 9×13‑inch serving dish. Spread half the mascarpone mixture over top of the lady fingers, smoothing with an offset spatula. Dip and arrange a second layer of lady fingers on top of the mascarpone layer. Smooth the remaining mascarpone over top. Chill several hours or overnight.

Before serving, dust the dessert with cocoa powder, completely covering the top with a thin layer of cocoa. (If dusted too early, the cocoa may turn muddy. It should remain powdery.)