Place the sugar-free lime gelatin in a mixing bowl. Pour in the boiling water and whisk until every gelatin crystal has completely dissolved.

Let the dissolved gelatin cool for several minutes until it is warm rather than hot. This cooling period keeps the cream cheese mixture smooth and prevents the whipped cream from melting later.

Beat the softened block-style cream cheese with the powdered keto sweetener until smooth and creamy. Add the lime juice and optional lime zest, then mix until evenly combined.

Gradually beat the cooled gelatin into the cream cheese mixture. Continue mixing until the color is even and the mixture has no visible lumps.

In a separate chilled bowl, whip the cold heavy cream to medium-stiff peaks. Stop mixing as soon as the cream holds its shape so it stays soft and creamy rather than grainy.

Fold the whipped cream into the lime mixture in two or three additions. Use a gentle spatula motion and avoid overmixing so the finished dessert remains airy.

Spoon the mixture into six small serving glasses or ramekins. Refrigerate for 2–4 hours, or until firmly set, then garnish with lime zest or whipped cream just before serving.