Place a metal or Pyrex bowl over a large pot of water to make sure the bowl fits securely and the bottom doesn’t touch the water.
Remove the bowl and bring the water to a simmer over medium heat.
Place the egg yolks, whole egg and sugar in the bowl. Whisk together for about 3 minutes, until pale yellow and well-blended. Carefully, place the bowl over the simmering water.
Whisk continuously for about 10 minutes, or until the mixture coats the back of the spoon. Add the Caravella Limoncello and whisk continuously for about 10 minutes, or until the mixture is the consistency of a medium-thick pastry cream.
If you are using the heavy cream, whisk it in now, until blended. Carefully, remove the bowl from the heat.
Spoon the zabaglione over the berries in the wine glasses. Serve immediately or chilled. Serves 6.