In a heatproof bowl over a pot of simmering water (double boiler), whisk egg yolks and sugar until thickened and pale, about 5–7 minutes. Remove from heat and let cool slightly.

In a separate bowl, whisk mascarpone cheese until smooth. Gently fold the cooled egg mixture into the mascarpone until combined.

In another bowl, whip heavy cream and vanilla extract until stiff peaks form. Gently fold the whipped cream into the mascarpone mixture. Set aside.

Prepare Coffee Soak

In a shallow bowl, combine cooled espresso, coffee liqueur, and sugar. Stir until sugar is dissolved. Set aside.

Assemble Tiramisu

Quickly dip each ladyfinger into the coffee mixture for 1-2 seconds and layer them in the bottom of a 9x9 inch dish or similar-sized container.

Spread half of the mascarpone cream over the ladyfingers and smooth the top.

Repeat with another layer of dipped ladyfingers and the remaining mascarpone cream. Smooth the surface.

Cover and refrigerate for at least 6 hours, preferably overnight.

Finish and Serve

Before serving, dust the top with unsweetened cocoa powder and optionally garnish with grated dark chocolate.