Step 1

Melt the chocolate in a large mixing  bowl over hot water or in the microwave in 30-second bursts.For detailed instructions see How to Melt Chocolate

Step 2

When the chocolate is almost melted, remove from the heat and stir until it's all melted

Step 3

Separate the eggs, being careful not to allow any of the yolk into the whites (or they won't whisk up)

Step 4

Put the yolks into a small bowl or cup. Put the whites into a medium bowl for whisking

Step 5

Whisk the egg whites into soft peaks.The tips will fall over onto themselves

Step 6

Use an electric hand-whisk or a balloon whisk, add the sugar, and whisk again briefly

Step 7

Stir the egg yolks quickly into the melted chocolate

Step 8

Whisk in a third of the egg white/sugar

Step 9

Fold the rest of the egg white very gently into the chocolate mixture with a metal spoon until just combined (be careful not to overmix).The idea is to keep as much air as possible in the mousse

Step 10

Put into bowls and refrigerate for at least four hours until set

Step 11

Decorate with cream if liked.