Begin by softening 8 ounces of cream cheese at room temperature for about 30 minutes.

In a mixing bowl, combine the softened cream cheese, 1 cup of sweetened condensed milk, and the freshly squeezed key lime juice with 1 tablespoon of key lime zest. Beat until smooth.

In a separate bowl, whip 1 cup of heavy whipping cream with 2 tablespoons of powdered sugar until stiff peaks form.

Gently fold the whipped cream into the mousse base until well incorporated.

Spoon the mousse mixture into prepared serving cups, filling them 3/4 full. Cover and refrigerate for at least 4 hours.

Before serving, top each cup with whipped cream, lime zest, and mini lime slices.