1. Simmer rhubarb, sugar and vanilla until soft. Puree and set aside to cool.
1. Prepare 6 4-oz ramekins by wrapping outsides with parchment rings that stand 2 inches above the lip of the ramekin. Secure parchment with butcher’s twine or an elastic band.
2. Over a pot of simmering water (or in the microwave) melt chocolate and set aside to cool. (Keep water simmering on the stove).
3. Whip cream to soft peaks and chill.
4. Whisk together egg yolks, water, brandy and 2 tbsp sugar for 2 minutes, to warm eggs. Whisk chocolate into egg yolk mixture and let sit until room temperature. Fold in whipped cream in 2 additions just until incorporated.
5. Whip egg whites to medium peak, and add 1 tbsp sugar and dash of salt. Fold a third into mousse followed by remaining two thirds. Fold in rhubarb quickly.
6. Pour or spoon mousse into ramekins, filling up over the edge of the ramekin. Freeze overnight (or at least 6 hours).
1. Simply remove parchment and garnish with a few fresh berries.