Ingredients     175g/6oz dark chocolate (70 per cent cocoa solids), chopped     110g/4oz butter, cut into cubes     3 large free-range eggs, separated     2 tablespoons of either rum, brandy or espresso coffee (according to preference) Preparation method     Melt the chocolate slowly in a heatproof bowl over a pan of barely simmering water.     Technique: Melting chocolate     Melting chocolateWatch technique1:07 mins     Remove the bowl from the heat and add the butter. Stir until melted and combined.     Add the egg yolks one by one, stirring constantly.     Add either the rum, brandy or espresso coffee (depending on your preference).     Whip the egg whites until soft peaks form when the whisk is removed, then gently fold them into the chocolate mixture.     Technique: Whipping cream by hand     Whipping cream by handWatch technique0:48 mins     Transfer the mousse to small cups or ramekins and refrigerate overnight, or until ready to serve. From bbc