Preheat the oven to 180c regular bake (or 170c fan bake). Grease a 20-25cm baking or pudding dish with butter.
Melt the chocolate with the butter, set aside.
Beat eggs, egg yolks, sugar, and vanilla until creamy.
Fold egg mixture into chocolate mixture, then sift in flour and baking powder.
Scrape into the baking dish.
Mix brown sugar, cocoa, hot water, and cream in a bowl; pour over the pudding mixture.
Bake for 45 minutes.
Dust with icing sugar and serve with ice cream or whipped cream.
