Directions

1. In a small saucepan over medium-high heat, put the lime juice, water, and 4 tablespoons of the rum until simmer. Cook until reduced to ½ cup total liquid. Remove from heat and set aside.

2. In another small saucepan over medium-high heat, bring the sugar and 1/4 cup of water to a simmer. Cook until thickened and syrupy, about 2 minutes. Remove from heat and stir in the remaining 2 tablespoons of rum. Set aside to cool.
3. In a mixing bowl, whisk the lime peel and juice for the glaze until combined well (you should have about ¼ cup). Cover it with plastic wrap and refrigerate until ready to use (can be made up to 2 days ahead).
4. Using an electric or hand mixer, beat the cream cheese or mascarpone cheese and egg whites until light and fluffy (about 3 minutes).
5. Add the vanilla extract, then add the reserved reduced lime juice mixture and any excess that may have accumulated while it cooled off (if any). Beat together until well combined - do not overbeat, or you'll end up with bubbles!
6. Spoon into glasses or bowls.