Separate eggs and yolks while eggs are cold. Place whites in a large bowl and yolks in a small bowl.

Whisk yolks until uniform.

Melt chocolate and butter in a microwave-proof bowl in 30-second bursts, stirring in between until smooth, then set aside to cool slightly.

Beat cream until stiff peaks form.

Add sugar to egg whites and beat until firm peaks form.

Fold egg yolks into cream using a rubber spatula - 8 folds max.

Check the chocolate temperature; it should be runny but warm (min 35C / 95F).

Pour chocolate into cream yolk mixture and fold through - 8 folds max.

Add 1/4 of beaten egg whites into chocolate mixture and fold through until incorporated.

Pour chocolate mixture into remaining egg whites and fold through until no white lumps remain.

Divide mixture between 4 small glasses or pots and refrigerate for at least 6 hours, preferably overnight.

Garnish with cream and chocolate shavings before serving.