Heat a pot of water that is big enough to hold your whisking bowl without Archimedes’ principle causing a flood on the stove. When the water is simmering, put all the ingredients except the cream into the bowl, preferably stainless steel, and then place the bowl in the water.
Whisk the ingredients together vigorously for 10 minutes, by which time they will have risen in volume and be thick and creamy.
Transfer the bowl on to another container, this time filled with a mixture of ice cubes and water. Whisk the sabayon vigorously until it is quite cold.