Let stand for a minute to soften the chocolate then whisk until smooth. Whisk in cocoa powder ... Divide chocolate mousse into serving bowls or glasses and refrigerate until ready to serve.
To make the mousse, beat the chilled crème pâtissière to remove any lumps before stirring in the melted chocolate. Mix in one third of the meringue, then gently fold in the rest followed by the ...
For the chocolate mousse, bring a little water to the boil ... Add the butter and dark chocolate and stir until melted, smooth and well combined. Remove from the heat and set aside to cool slightly.