Place the cottage cheese, unsweetened cocoa powder, maple syrup or honey, vanilla extract, and a pinch of salt into the jar of a high-speed blender or the bowl of a food processor.
Process the mixture on high speed for about 1 to 2 minutes. Stop halfway through to scrape down the sides with a spatula to ensure every bit of cottage cheese is fully incorporated and no lumps remain.
Check the thickness of your mousse. If it feels too stiff for your liking, add 1 to 2 tablespoons of milk (dairy or plant-based) and blend again for a few seconds until your desired creaminess is reached.
Give the mousse a quick taste. If you prefer a sweeter dessert, add an extra teaspoon of your chosen sweetener and pulse briefly to combine.
Transfer the mixture into small individual bowls or ramekins. While you can eat it immediately, chilling it in the refrigerator for at least 30 minutes allows the flavors to meld and the texture to set into a firmer, more traditional mousse feel.
Once chilled, top with your favorite garnishes like fresh berries, a dollop of whipped cream, or a sprinkle of dark chocolate shavings before serving.