Before gathering your ingredients, place mixing bowl and beaters in the freezer to chill 5-10 minutes. Chilling the bowl will help the whipped cream whip up faster and fluffier.
In a small bowl, add 2 T. water. Sprinkle gelatin over water, stir, then set aside for 1 minute to allow the gelatin to absorb the water.
Pour the hot coffee into the bowl of gelatin and stir until the gelatin is completely dissolved. Once fully dissolved, set aside to cool.
Retrieve your chilled mixing bowl and add heavy cream. Beat cream on medium-high speed 1-2 minutes until it begins to thicken. Reduce speed to low, then while still mixing, slowly add powdered sugar, then cocoa powder and vanilla.
Continue mixing, and slowly pour in the cooled coffee/gelatin mixture.
Return mixer to medium or medium-high speed and continue to beat until well blended, fluffy and soft peaks form. Do not over-mix. The mixture will firm up as it chills.
Spoon or pipe (with a piping bag) into your choice of small glasses or dishes. Chill at least 30 minutes before serving.
Before serving, garnish with chocolate covered espresso beans, chocolate sprinkles, or your choice of garnish.
The mousse can be made several hours in advance (and kept in the refrigerator), but I would suggest serving it the same day it's made.