Step 1

Mix all the ingredients in a stainless steel bowl (ideally a bowl with a convex base); use the bowl as a double boiler over barely boiling water and stir with a whisk until you obtain a rather dense and airy mousse;

Step 2

mix with regular but not overly fast movement and accelerate when the zabaglione starts to become denser (it will take about 15 minutes). Serve immediately, accompanied by panettone or pandoro.