Roughly break up the chocolate, place it in a microwave-safe bowl, and cook for one minute. Stir, then continue cooking in 30 second bursts - stirring between each burst - until the chocolate has melted. Stir in ¼ cup of the heavy cream.

Place the egg whites in a stand mixer and beat until stiff peaks form. In a separate bowl, whip some heavy cream until stiff. For best results, chill the bowl and whisk beater in advance.

Fold half of the whipped cream into the melted chocolate, then gently stir in the rest. Then carefully fold in the egg whites. You want to keep as much air in the mixture as possible, so work slowly!

Spoon the mousse into serving bowls or glasses - or you can use a piping bag.

Store in the fridge until required. To serve, add some whipped cream and then grate a little chocolate over the top.