Classic French Chocolate Mousse

Method

1. 1Carefully separate the egg yolks from the whites into two separate clean mixing bowls.
2. 2Chop the dark chocolate and melt it together with the butter in a heatproof bowl set over a pan of barely simmering water, then set aside to cool to room temperature.
3. 3Whisk the egg yolks into the cooled melted chocolate until glossy and thoroughly combined.
4. 4Add a pinch of salt to the egg whites and beat with an electric whisk until soft peaks form, then gradually add sugar and beat until firm and glossy.
5. 5Fold one third of the whipped whites into the chocolate mixture to lighten it, then gently fold in the remaining whites. Spoon into glasses, chill for at least 4 hours, and top with raspberries.