To make the sponge, melt the chocolate with the coffee in a bowl over a pan of hot water. Leave to cool slightly. Beat the egg yolks until smooth then add the caster sugar. Continue to beat until pale and the mixture trails off the whisk in ribbons. In a separate bowl, beat the egg whites and salt until they form soft peaks. Add the melted chocolate to the egg yolk mix then fold in the egg whites. Spread on to the lined baking tray to between
Make the mousse but do not allow it to set. Cut out four rings from the sponge the same diameter as the flan rings, and place them in the bottom of the rings. The sponge can now be flavoured with a little rum or liqueur, if required. Spoon the mousse into the moulds on top of the sponge, chill and leave to set.
When the mousses are set, lift off the flan rings and carefully take off the paper. Finish with the whipped cream and grated chocolate of the mousse recipe. Place the mousses on plates and serve with your chosen sauce and a sprig of mint.