Streusel: Mix all the ingredients in a bowl (I use the paddle attachment) until you achieve a crumble like texture and the ingredients are well incorporated. Make sure to keep and eye on it and don’t over mix it otherwise you’ll have one dough instead of a crumbly texture. (Leftovers can be frozen) Kuchen: Mix the water, butter and dark chocolate in a bowl and melt over a Bain Marie. ( I melt it in my KitchenAid bowl) Mix the flour, salt, baking powder and the cocoa powder. Set aside Mix the wet ingredients: milk and oil and mix slightly. Once the butter and chocolate is melted transfer the bowl into your KitchenAid. With the paddle attachment add in the sugar and mix well. Add the eggs one by one. Alternatively add the dry ingredients and the milk-oil mixture. Make sure to scrape down the sides to avoid flour clumps. Add the smashed banana and the peanut butter. Mix well until incorporated and you have a smooth and even batter. Fill into your prepared moulds. Add the banana slices and press slightly into the batter. Add the streusel topping and bake at 175C for about 40-45 minutes. (You can insert a skewer to check if it is done. Should come out clean) Once completely cooled, drizzle with the peanut butter.