Preheat oven to 180°C. Line a small baking dish with baking paper.
Place butter, brown sugar and cocoa powder in a medium pot on medium heat. Stir continuously, until butter has melted. Remove from heat.
In a large bowl, whisk eggs with electric beaters for about 3 minutes until pale and fluffy
Pour chocolate mixture and flour into eggs and mix quickly to combine
Transfer to prepared dish and bake for 30 minutes. The brownie will be gooey in the middle.
Top with freeze-dried raspberry powder and serve in bowls with cream or ice cream.