01 - Combine mascarpone cheese, lemon zest, lemon juice, sugar, and vanilla extract in a large mixing bowl. Beat with hand mixer on medium speed until completely smooth and well incorporated.
02 - In a separate clean bowl, whip cold heavy cream using hand mixer until stiff peaks form. Be careful not to overwhip.
03 - Gently fold whipped cream into mascarpone base in two additions using a spatula. Incorporate fully until mixture becomes light, airy, and uniform in color.
04 - Spoon or pipe mousse evenly into individual serving glasses or bowls. Smooth tops with spatula for clean presentation.
05 - Cover containers with plastic wrap and refrigerate for minimum 2 hours until mousse is fully set and thoroughly chilled.
06 - Just before serving, top with fresh berries, sprinkle additional lemon zest, and garnish with mint leaves if desired.