01 - In a large mixing bowl, combine the mascarpone cheese, lemon zest, lemon juice, sugar, and vanilla extract. Beat with a hand mixer on medium speed until smooth and well combined.
02 - In a separate bowl, whip the heavy cream to stiff peaks using a hand mixer or stand mixer.
03 - Gently fold the whipped cream into the mascarpone mixture in two additions, using a spatula, until fully incorporated and light.
04 - Spoon or pipe the mousse evenly into serving glasses or bowls.
05 - Cover and refrigerate for at least 2 hours, or until set and chilled.
06 - Garnish with fresh berries, a sprinkle of lemon zest, and mint leaves just before serving, if desired.