Mix the banana, fish cheese, yogurt and 1 tablespoon of the baking cocoa. Add sweetener. If you like it chunky, just mash the banana, otherwise puree the cream. Now put in the freezer and mix about every half hour to prevent crystallization.
For the brownie:
For the cup brownie, mix all the remaining ingredients in a large cup to form a batter. Bake this in the microwave on the highest setting for about a minute. As soon as the brownie has cooled, crumble into pieces and mix with the cream.
Your Chocolate Fudge Brownie will be ready after about 3 - 4 hours (depending on how you like the consistency).