In a bowl, beat egg yolks with ¼ cup of sugar until pale and doubled in volume, about 5 minutes.
In another bowl, beat heavy cream, vanilla, and remaining ¼ cup of sugar until medium peaks form. Add mascarpone and mix until smooth. Fold this into the egg yolk mixture.
Mix espresso and Irish cream in a shallow bowl.
Sprinkle cocoa powder evenly over the bottom of your baking dish.
Dip each ladyfinger in the espresso mixture, counting to 3 on each side, and layer them in the dish.
Spread half the mascarpone mixture over the ladyfingers and dust with cocoa powder.
Repeat with another layer of dipped ladyfingers, then top with remaining mascarpone mixture.
Dust with cocoa powder, sprinkle chocolate shavings, and refrigerate for at least 6 hours (overnight preferred).
Serve in scoops or cut into squares for a beautiful presentation.
Enjoy the indulgent layers of coffee, cream, and chocolate in this classic tiramisu!