You will love this.

I am not sure how many carbs this has.
Maybe someone here can do the math for us.
In mug with hight sides place;

1/2 cup cold whipping cream - really heavy cream at least 35% fat
Tablespoon of cocoa unsweetened
Drop of vanilla extract
Stevia or Equal to taste

Take braun hand mixer and spin like crazy until it thickens. Takes less then 1/2 a minute.
Use miniture spatula to get all of it out of the mixer head. Don't waste any of it.