Bloom the gelatin by mixing the gelatin and cold water together in a small bowl. Let stand for 5 minutes.
Add the sugar, cocoa, vanilla, and 1/2 cup whipping cream to a sauce pan. Heat while stirring constantly until just about boiling. Don't let it come to a full boil.
Add bloomed gelatin to sauce pan and stir until completely dissolved. Add the remaining 1/2 cup whipping cream.
Strain the mixture to remove any clumps.
Let it cool slightly before using.