Preheat the oven to 170°C conventional (150°C fan-forced). Grease a 1.25 litre baking dish with butter.
Start with the topping. Combine the brown sugar and cocoa powder in a bowl. Crush any lumps with a fork. Don’t pour in the boiling water yet. That is used later. Set aside.
For the batter: Combine the dry ingredients first – plain flour, baking powder, caster sugar, cocoa powder and salt. Stir well.
In a separate bowl, combine the wet ingredients – milk, butter, egg and vanilla. Whisk until well combined.
Mix the wet ingredients into the dry and combine well. The batter will be quite thick.
Pour the batter into the baking dish and spread it out evenly. Sprinkle over the topping evenly so that all areas are well covered.
Slowly and carefully, pour the boiling water over the back of a large metal spoon to cover the pudding (see video). Place the dish on a baking tray. Bake for 30–35 minutes or until the pudding bounces back when pressed gently in the centre.
Serve with good quality vanilla ice cream. OMG, yum!