Preheat the oven to 180 °C for the banana brownies. Mix granulated sugar, vanilla sugar and Rama. Mix in the eggs.
Mash the bananas with a fork or simply mash them with your (washed!) hands and mix into the mixture.
Sift flour, cocoa and baking powder over banana mixture and fold in. Stir in the sour cream.
Grease a pan, pour in the batter and bake the banana brownies for 35-40 minutes.