Heat the cream and milk

• Pour the double cream and whole milk into a saucepan.
• Warm gently over low heat until steaming, without boiling.

Melt in the chocolate

• Remove from the heat and add the chopped dark chocolate.
• Whisk until completely smooth and glossy.

Incorporate the yolks

• Whisk the egg yolks into the warm chocolate mixture until fully combined.

Whip the egg whites

• Beat the egg whites in a clean bowl, adding the sugar gradually.
• Continue until stiff, glossy peaks form.

Fold together

• Fold a third of the whipped whites into the chocolate base to loosen it.
• Gently fold in the remaining whites in two additions, keeping the air in.

Chill and serve

• Divide the mousse into glasses or ramekins.
• Refrigerate until set and firm.