Serves six to eight
YOU WILL NEED
170g good-quality dark chocolate, broken into small pieces
170g unsalted butter
3 tbsps good-quality instant coffee granules, mixed with 2 tbsps hot water
4 free-range eggs, separated
150g caster sugar, plus 1 tbsp extra
2 tbsps Irish whiskey, or dark rum
Pinch fine salt
Whipped cream, to serve
Bring a medium-sized saucepan of water to a gentle simmer and melt the chocolate, butter and coffee in a heatproof bowl that fits snugly over the pan without touching the water, stirring occasionally.
Carefully remove the bowl from the heat and set aside. Keep the saucepan of water simmering away. Place a few handfuls of ice in a large bowl and half-fill with water. Set aside nearby.
Sit a heatproof bowl that will fit into the bowl of ice over the saucepan of simmering water and add the four egg yolks, 150g caster sugar, whiskey/rum and one tablespoon of cold water.
Using a balloon whisk or hand-held electric beaters, whisk for about three minutes until the mixture thickens, becomes paler and has a similar consistency to that of runny mayonnaise.
Remove the bowl from the heat and place it in the bowl of iced water. Continue to whisk for a few minutes more until the mixture thickens and cools slightly, being careful that no water gets into the mixture. Add the chocolate mixture to the beaten egg mixture and stir to combine.
Whisk the egg whites with a pinch of salt until just stiff and frothy. Add the extra tablespoon of caster sugar and beat again until just glossy.
Using a large mixing spoon, add one spoonful of egg whites to the chocolate mix and fold it in gently. Gradually fold in the remaining egg white, taking care not to over mix. Transfer the mousse to a jug, then pour into individual serving jars or glasses. Place in the fridge and chill for three to four hours before serving. Serve topped with a thick layer of whipped cream.