You will need


Place the water and dark chocolate chips into a large heatproof bowl and sit over a pan of simmering water but do not let the base of the bowl touch the water. Heat gently, stirring constantly, until all the chocolate is melted. Alternatively you can heat them up in the microwave in 30 seconds intervals (make sure to stir them so they don't burn).

Remove the pan from the heat and allow to cool slightly. Stir in the egg yolks until thoroughly mixed in.

Whisk the egg whites and lemon juice in a separate, large (clean) bowl until it forms soft peaks (the lemon juice is used to stabilise the egg whites). Add the gold caster sugar and continue to whisk until firm peaks form. Take care not to over whisk at this point, otherwise the whites will start to separate with a runny liquid residue left at the base of the bowl and you will lose all the air that you have just whisked in.

Whisk about a third of the chocolate into the egg whites, rapidly. Then, using a spatula lightly fold the remaining egg whites. Make sure the two mixtures are well combined but try not to over fold as, again, you will lose the air.

Spoon the mixture into your serving dishes. This is enough to make 4 large servings or 6 smaller ones.

Top the mousse with white and dark chocolate shavings, white and dark chocolate shards and blueberries or raspberries. Thoroughly chill the mousse in the fridge (2-3 hours).

This mousse can be made ahead of time and stored in the fridge for up to 3-4 days. It is also possible to freeze for up to one month, as long as it is stored in an airtight container.