Tiramisù

Brew 300 ml of espresso, or very strong filter coffee, and pour it into a shallow dish wide enough to dip a sponge finger lengthwise. Let it cool completely, which takes about 20 minutes; hot coffee turns the biscuits to mush at once. Meanwhile, separate the eggs carefully, keeping every trace of white out of the yolks, and take the mascarpone out of the refrigerator so it loses its chill.

• espresso300 mL

Put the egg yolks and the sugar in a large bowl. Whisk with an electric whisk, or by hand with a balloon whisk, for 4–5 minutes, until the mixture has doubled in volume, turned pale yellow and falls from the whisk in a thick ribbon. The sugar must be fully dissolved: rub a little between your fingers and it should feel smooth, not gritty.

• egg yolk5
• sugar100 g

Add the mascarpone to the yolks, one third at a time. Fold it in gently with a spatula, drawing it from the bottom of the bowl to the top, until the cream is smooth, thick and without lumps. Do not whisk hard at this stage: overworked mascarpone turns grainy and then splits. The cream should hold a soft peak and not run when you lift a spoonful.

• mascarpone500 g

Dip each sponge finger in the espresso for 1–2 seconds per side, so it is moist but still firm, and lay half of them in a single layer in a 20 × 30 cm dish. Spread half of the cream evenly over the top. Repeat with a second layer of dipped biscuits and the rest of the cream, and smooth the surface with the back of a spoon.

• savoiardi (sponge fingers)300 g
• espresso300 mL

Cover the dish and refrigerate for at least 6 hours, ideally overnight, so the biscuits soften through and the cream sets firm enough to slice. Just before serving, dust the top with the cocoa through a fine sieve, in an even layer. Cut into 8 squares with a knife dipped in hot water and wiped dry, and lift them out with a spatula.

• cocoa powder2 tbsp