Add the water to a small bowl. Sprinkle the gelatin over the water and allow to sit for a few a minutes to soften.

While the gelatin is softening, prepare the raspberries. Place thawed berries and ½ cup white sugar in a blender. Process on medium speed until smooth. Place a fine mesh sieve over a medium-size bowl. Strain berry puree through the sieve, pressing and stirring as needed to separate the berry puree from the seeds. Discard seeds.

Place the small bowl of gelatin in the microwave. Heat for 10 seconds on 30% power; stir well to dissolve gelatin. Repeat if needed. Add the dissolved gelatin to the raspberry puree. Stir well to incorporate the gelatin into the puree. Cover bowl and refrigerate puree for about 1 hour until chilled and soft set.

To a large mixing bowl, add the whipping cream, remaining ¼ cup sugar and the vanilla. Beat with an electric mixer until moderately stiff peaks form. Remove 3/4 cup whipped cream, cover and refrigerate.

Beat the raspberry puree with the mixer for about 30 seconds. (It is not necessary to wash the beaters between whipping the cream and beating the puree.) Add the puree to the remaining whipped cream. Fold together well. Divide the mousse evenly between 8 dessert dishes. Cover and refrigerate for at least 1 hour and up to overnight.

To make the balsamic reduction: In a small sauce pot, over medium heat, bring the balsamic vinegar to a boil. Lower heat and let vinegar simmer until reduced by half (1/4 cup), about 7-10 minutes, stirring frequently. Watch carefully so that the vinegar does not burn. If the reduction gets too thick, add a small amount of vinegar to thin it out. Cool before serving.

Finishing: Just prior to serving, top each dessert with a small dollop of the reserved whipped cream, two raspberries and a mint leaf. Drizzle each dessert with 1 ½ teaspoons of the balsamic reduction. Serve immediately.