In a medium bowl, whisk together the egg yolks and sugar until smooth and creamy.

Next, place the bowl over a double boiler (or a heatproof bowl set over simmering water) and whisk constantly for about 5–7 minutes until it thickens slightly. This step helps cook the yolks safely and gives the mixture that rich, custardy flavor.

Remove it from the heat and let it cool slightly.

Once the mixture has cooled, gently fold in the mascarpone cheese until it’s fully combined and smooth. Don’t rush this, slow and gentle keeps the mixture fluffy and creamy.

In a separate bowl, whip the heavy cream and vanilla extract until stiff peaks form. You’ll know it’s ready when it holds its shape.

Then, carefully fold the whipped cream into the mascarpone mixture. What you’ll get is the silkiest, dreamiest filling ever!

In a shallow dish, mix the cooled espresso with the rum or coffee liqueur if you’re using it.

Quickly dip each ladyfinger into the espresso mixture. Don’t let them soak too long or they’ll fall apart, just a quick dunk will do.

Lay them in a single layer at the bottom of a 9×9-inch dish (or similar-sized serving dish).

Spread half of your mascarpone cream mixture over the soaked ladyfingers. Then repeat with another layer of espresso-dipped ladyfingers and finish with the rest of the cream.

Cover the dish and refrigerate for at least 4 hours, or overnight if you can wait that long. (Overnight gives it the best texture and flavor, worth the patience!)

Right before serving, dust the top with a generous layer of cocoa powder and sprinkle with dark chocolate shavings if you’re feeling extra fancy.