Remove seed and peel from the avocados, then place in a blender with cocoa powder, Greek yogurt, maple syrup, vanilla extract and salt.
Blend on high until smooth and free of lumps. If you don’t have a blender, add the avocados to a bowl and mash with a fork. Then, add all other ingredients, and mix until smooth.
Enjoy immediately, or refrigerate for at least 1 hour before serving. The extra chilling time will make the mousse richer, creamier, and more flavorful.