In a large mixing bowl, beat the softened cream cheese and granulated sugar together until smooth and creamy. Add in the lemon juice, lemon zest, and vanilla extract. Mix until well combined and fluffy.

In a separate bowl, whip the cold heavy cream until stiff peaks form. This gives the mousse its signature lightness and volume.

Gently fold the whipped cream into the lemon cream cheese mixture. Be careful not to deflate the whipped cream—use a spatula and fold slowly until fully incorporated and smooth.

Spoon the mousse into individual serving cups or small bowls. Refrigerate for at least 1 hour to let the flavors develop and the texture set.

Before serving, top each cup with optional garnishes like crushed graham crackers, a dollop of whipped cream, extra lemon zest, or fresh berries for color and flavor.