Wash and zest the lemons, reserving a little zest for the final garnish.

Juice the lemons until you have 50 ml lemon juice.

Strain the 50 ml lemon juice to remove pulp and seeds.

Add 500 g fresh whipping cream and 160 g icing sugar to a large mixing bowl.

Whip the sweetened cream on low speed, then increase to high speed until medium-stiff peaks form.

Put 500 g mascarpone cheese in the second mixing bowl and add the strained lemon juice.

Mix the mascarpone and lemon juice until smooth, then stir in most of the lemon zest.

Fold half of the whipped cream into the lemon mascarpone mixture using gentle bottom-to-top strokes.

Fold in the remaining whipped cream just until the mousse is evenly combined and airy.

Divide the lemon mousse among 6 serving glasses and garnish with the reserved lemon zest.

Chill the mousse until cold and slightly set before serving.