Whisk the yolks with sugar

• Separate the eggs, keeping the yolks and whites in separate bowls.
• Add the sugar to the egg yolks and mix until pale yellow and slightly thickened.
• Mix in the vanilla extract if using.

Fold in the mascarpone

• Fold the mascarpone into the yolk mixture and mix until just smooth.

Whip the egg whites

• Beat the egg whites until stiff peaks form; the bowl should hold them in place when flipped over.

Combine the cream

• Fold the stiff egg whites gently into the mascarpone mixture until evenly combined.

Layer the tiramisu

• Spread a little of the cream mixture in the bottom of the dish.
• Dunk the ladyfingers briefly in the coffee and arrange a layer in the dish.
• Cover with cream, then repeat the layers with the remaining ladyfingers and cream.

Chill overnight

• Cover and let rest in the fridge overnight.

Dust and serve

• Dust generously with cocoa powder just before serving.