Start by making what the Italians call a zabaglione (or sabayon in France) – a close cousin of eggnog. Place the egg yolks, sugar, rum, vanilla, and nutmeg in a bowl and set it over a pot of gently simmering water, ensuring that the bottom of the bowl does not touch the water. Begin whisking the egg mixture continuously for several minutes until it begins to thicken and lighten in colour. This should take about 7 or 8 minutes. When complete, set aside to cool slightly.

Whisk the cream to stiff peaks using a stand mixer, electric handheld mixer, or simply a whisk.

Whisk the mascarpone for about a minute to lighten it. This is much easier when the mascarpone is at room temperature.

To assemble the tiramisu, choose a rectangular casserole dish about 9 inch x 14 inch (22.5 cm x 35 cm) and begin by dipping each ladyfinger quickly into the espresso or brewed coffee. Cover the bottom of the dish with the first 20 biscuits.

Fold the zabaglione into the mascarpone cheese first, then gently fold in the whipped cream. Try to keep the mixture as light as possible while not overworking it.

Spread half of this mixture evenly over the ladyfingers, then repeat this and create a second layer with the remaining biscuits and cheese mixture.

Using a box grater or microplane tool, finely grate the white chocolate over the top of the cream.

Refrigerate the tiramisu until ready to serve. Allowing it to set for several hours or even overnight is ideal.