Pour the light and dark beers into a large saucepan. Stir in the sugar, pepper, cinnamon, salt and nutmeg and bring to a boil.
In a small bowl, whisk together the egg yolks and cream. Whisk in a little bit of the hot beer so the mixture warms without scrambling the yolks. Stir into the beer while whisking constantly over low heat to avoid curdling. Refrigerate until cold.
Just before serving, whip egg whites in a medium bowl until stiff but not dry. Fold them into the soup and serve.