In a heatproof jug, place the cold water and sprinkle over the gelatin. Allow to sit for 2 minutes.
Add the ¼ cup of hot water and stir until dissolved. If you’re left with undissolved gelatin, place the jug into the microwave and heat for 30 seconds, or until the gelatin has dissolved. Set aside to cool.
Dissolve the instant coffee in the ½ cup of hot water and set aside to cool.
In your stand mixer, add the erythritol, cacao and vanilla extract. Using the whisk attachment gently mix the ingredients.
Add the cream to the stand mixer and whisk to soft peaks.
With the mixer on low speed, add the dissolved coffee until it is combined.
Add the gelatin and mix until combined.
Pour the mousse into 8 glasses and set in the fridge for 2 hours.
Serve topped with a dollop of whipped cream and enjoy.