Step 1: Prepare the gelatin

Soak the gelatin leaves in cold water for 5-10 minutes until soft. If using powdered gelatin, follow the packet instructions to bloom it in water.

Step 2: Heat the lemon juice and sugar

In a small saucepan, combine the lemon juice and caster sugar. Heat gently over low heat, stirring until the sugar dissolves. Remove from the heat, squeeze out the excess water from the softened gelatin, and stir it into the warm lemon mixture until fully dissolved. Set aside to cool slightly.

Step 3: Whip the cream

In a mixing bowl, whip the double cream until soft peaks form. Set aside.

Step 4: Whisk the egg whites

In a separate clean bowl, whisk the egg whites until stiff peaks form.

Step 5: Combine the mousse

Fold the lemon mixture into the whipped cream gently to retain its airy texture. Then, carefully fold in the beaten egg whites until fully incorporated.

Step 6: Pour and chill

Divide the mixture evenly between serving glasses or ramekins. Cover and refrigerate for at least 3-4 hours, or until set.

Step 7: Garnish and serve

Garnish with fresh berries, mint leaves, or a sprinkle of lemon zest before serving.