01 - Beat the softened cream cheese in a medium bowl using a hand mixer until smooth and fluffy consistency is achieved.
02 - Add granulated sugar, lemon zest, fresh lemon juice, and vanilla extract to the cream cheese mixture. Beat until thoroughly incorporated and creamy.
03 - In a separate chilled bowl, whip the heavy cream with powdered sugar using electric beaters until stiff peaks form and mixture holds its shape.
04 - Gently fold the whipped cream into the lemon cheesecake mixture using a spatula, followed by the sour cream, until fully incorporated and mixture becomes light and airy.
05 - Spoon or pipe the mousse mixture into individual serving glasses or bowls, filling each about three-quarters full.
06 - Cover serving vessels with plastic wrap and refrigerate for at least 2 hours to allow mousse to set properly and develop firm texture.
07 - Remove from refrigerator and top with additional lemon zest, fresh berries, and crushed graham crackers or shortbread cookies just before serving.