Melt the butter in a small pot, remove from the heat and let it cool down. Mix flour, baking powder, 25 g cocoa and 110 g brown sugar well in a mixing bowl.
Mix milk, egg and melted butter. Pour into the mixing bowl with the dry ingredients and mix well. (The dough is very firm.) Pour the dough evenly into 6 greased ovenproof moulds (approx. 300 ml each).
Brush smooth.
Mix 35 g cocoa and 110 g brown sugar. Spread about 2/3 of the cocoa-sugar mixture evenly on the dough in the moulds. Pour 425 ml boiling water evenly into the 6 moulds on the dough.
Place on a baking tray and bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for 35-40 minutes. Remove from the oven and sprinkle with remaining cocoa-sugar mixture.
Serve warm. Serve with vanilla ice cream sprinkled with cocoa-sugar mixture.