Safe Tiramisu with Pasteurized Egg Yolks

Brew a very strong espresso. You can use a pressure coffee maker, a moka pot, or a strong brew of instant coffee. You need about 300 ml of liquid. Pour the hot coffee into a wide, flat dish (e.g., a deep plate or bowl) and set it aside to cool completely. This is very important because hot coffee would soak the ladyfingers. Once the coffee is cold, add the Amaretto liqueur (if using) and mix.

Prepare a water bath. Pour water into a small pot to a height of about 3-4 cm and bring it to a gentle simmer (only small bubbles should appear, the water should not be boiling vigorously). Place a heatproof bowl (metal or glass) on top of the pot, ensuring that its bottom does not touch the surface of the water. In the bowl, add the egg yolks, sugar, and a pinch of salt. Start whisking everything immediately with a whisk or a hand mixer on low speed.

Whisk the egg yolk mixture continuously for about 8-10 minutes. The mixture will gradually thicken, lighten in color, and increase in volume. The finished cream should have the consistency of thick pudding, be pale yellow, and fluffy. When you lift the whisk, a distinct 'ribbon' should remain on the surface. This process heats the yolks to a safe temperature (about 70°C), eliminating the risk of bacteria. Remove the bowl from the pot and set aside to cool completely, stirring occasionally to prevent a skin from forming on the surface.

In a large bowl, place the chilled mascarpone cheese. Use a silicone spatula or wooden spoon to gently mix it for a few seconds to achieve a creamier consistency. Do not use a mixer at this stage, as mascarpone can easily curdle. Add the completely cooled egg yolk mixture (Zabaglione) to the mixed cheese.

Using a spatula, very gently combine the yolk mixture with the mascarpone cheese. Make slow, circular motions from the bottom of the bowl upwards, as if you are 'scooping' the mixture. Mix only until the ingredients are combined and a uniform, smooth cream is formed. Too vigorous or prolonged mixing may cause the cream to become runny.

Prepare a dish, preferably glass or ceramic, measuring about 20x30 cm. Spread a thin layer of the prepared cream on the bottom. This will be the 'glue' for the first layer of ladyfingers. Take the ladyfingers one by one, dip them VERY briefly (literally for 1 second on each side) in the cooled coffee, and arrange them tightly next to each other on the layer of cream.

Spread half of the remaining mascarpone cream evenly over the layer of ladyfingers. Smooth the surface with a spatula or the back of a spoon. Then, place a second layer of ladyfingers, also briefly dipped in coffee. Top with the remaining cream and carefully smooth it out to create a smooth surface.

Cover the dish with plastic wrap and place it in the refrigerator for at least 4-6 hours, preferably overnight. Chilling is key for the flavors to meld, the biscuits to soften, and the cream to set, making it easier to slice. Just before serving, dust the top of the dessert generously with unsweetened cocoa powder, sifting it through a small sieve for an even layer.