Directions

1. Separate egg whites and yolks into two bowls. Lightly whisk the yolks.
2. Place the chocolate and butter in a microwave-safe bowl. Melt in 30-second intervals, stirring between each, until smooth. Set aside to cool.
3. Beat the cream until stiff peaks form.
4. Beat the egg whites until foamy. Add the caster sugar and continue whipping until firm peaks form.
5. Gently fold the whisked egg yolks into the whipped cream using a spatula (about 8 folds; streaks are fine).
6. Check the chocolate temperature: it should be runny and lukewarm. If it has thickened, microwave for 2 × 3-second bursts to loosen.
7. Pour the melted chocolate into the cream-yolk mixture and fold gently (8 folds max; streaks ok).
8. Add 1/4 of the whipped egg whites into the chocolate mixture. Fold until incorporated, smearing as needed (about 10 folds).
9. Pour the chocolate mixture over the remaining egg whites. Fold gently until fully combined with no white streaks left (approx. 12 folds).
10. Divide the mousse into 4 small glasses or pots. Refrigerate for at least 5 hours, ideally overnight.
11. To serve, top with whipped cream and chocolate shavings.