In a blender or food process, combine the cottage cheese, chocolate protein powder, and espresso powder. Blend until smooth.
In a large bowl, combine the heavy cream, sweetener, cocoa powder, and vanilla extract. Beat together until the cream holds stiff peaks.
Add the cottage cheese mixture to the whipped cream, gently folding together to avoid deflating the peaks as much as possible.
Divide the mixture between 4 dessert glasses and chill until it firms up, 1 to 2 hours.
Notes
Storage Information: Store the mousse in the fridge for up to 5 days. Sweetener Options: This recipe does not rely on the sweetener for consistency or texture so feel free to use what you like best. It should be a powdered version to avoid any grittiness.