Place your mixing bowl and whisk into the refrigerator to chill.
In a metal measuring cup or a very small saucepan combine the water and the gelatin. Let this sit for 5 minutes then place over low heat for 2 minutes to melt.
With your mixer on low combine the cream and the cocoa in the chilled bowl. Drizzle in the melted gelatin. Add the vanilla and turn mixer to high and whip to medium peaks