Discussion
Sometimes when I made this mousse it was either granular or too solid. Having the ingredients just at body temperature when mixing the eggs and chocolate seemed to solve both problems. A manual whisk will do but the processes are much more quicker with an electric whisk - particularly when finishing the egg whites which can still take 5 or 10 minutes.
Have three bowls ready. Then prepare a saucepan with about an inch of water and over which the bowl will sit without touching the water and bring to nearly simmering.
Add the egg yolks and 4oz sugar to the bowl and whisk them until hot and creamy but not so hot so that they are scrambled. Transfer the bowl and sit it in cold water and continue whisking until it reaches body temperature. (Optionally stir in a tablespoonful of orange liqeur at this stage).
Add the chocolate and butter to another bowl and allow them to melt over the saucepan of nearly boiling water, while the egg mix is cooling. (Optionally add an expresso coffee or two teaspoons of coffee granules melted in a few drops of water to the mixture).
Add a pinch of salt to the egg whites and beat them until soft peaks are formed. Add 2 oz sugar to the mix and beat until hard peaks form and the whole mixture appears glossy. This can take some time.
Combine the egg and chocolate mixtures (and optionally add 1 oz finely diced glazed orange peel). Quickly spoon in one or two tablespoons of the egg whites to make the mixture nice and loose. (Delaying at this stage can result in the mixture going very solid). Then keep adding spoonfuls of egg white carefully folding them into the mix until fully incorporated. The word is incorporated and not mixed into a homogenised whole with all the air knocked-out. Spoon the mixture into glasses or ramekins and refrigerate until set.
Serve with whipped or double cream and chards of grated chooolate or broken pieces of Cadbury's chocolate flake to your own individual preference.
Garnish with a mint or basil leaf to make it look pretty.