Instructions

1. Heat the lemon juice and sugar in a saucepan over medium heat until the sugar dissolves, stirring constantly.
2. In a separate bowl, beat the eggs until they become light and fluffy.
3. Gradually pour the hot lemon mixture into the beaten eggs while continuously whisking to prevent the eggs from scrambling.
4. Return the egg-lemon mixture to the saucepan, and cook over low heat while stirring until the mixture thickens.
5. In a small bowl, dissolve the gelatin in water and let it bloom for about 5 minutes.
6. Add the bloomed gelatin to the lemon mixture and stir until it's well combined. Remove from heat and allow to cool to room temperature.
7. While the lemon mixture is cooling, whip the cream until stiff peaks form.
8. Gently fold the whipped cream into the cooled lemon mixture until well combined.
9. In a food processor, crush the digestive biscuits until fine crumbs form. Combine the crumbs with the melted butter.
10. Press the biscuit-butter mixture into the bottom of serving glasses or a baking dish to form a crust.
11. Pour the lemon cream mixture over the biscuit crust.
12. Refrigerate for at least 4 hours, or overnight for best results, until the mousse is set.
13. Before serving, garnish with additional lemon zest.