- Place the cream, lemon zest of two lemons and sugar in a large bowl and whisk together to combine. Add the juice of one lemon and whisk again to combine well.
- In a clean bowl, whisk the egg whites until they form soft peaks. Fold egg whites only into the lemon cream mixture.
- Spoon the mousse into four serving glasses and chill. Decorate with extra lemon zest if desired.