Add the gelatin and cold water to a small bowl and allow it to sit for 2 minutes. Add hot water and stir until the gelatin is dissolved.
Cooks Note: If you are using modified tapioca starch, this step is not necessary just add it to cocoa mixture and continue.
In a stand mixer, add the cocoa and sugar and blend on low speed with the whisk attachment, until well combined. Add the cream, vanilla bean seeds and coffee and mix on high speed until stiff peaks are formed. Stir in the gelatin and mix for 1 minute. Remove the mousse from the mixer and portion into serving dishes. Refrigerate for 1 to 2 hours. Garnish with shaved chocolate or fresh fruit and serve.