Grease six ovenproof moulds (approx. 300 ml each). Melt 60 g butter in a small pot, remove from heat and let it cool down. Mix flour, baking powder, 3 tbsp. cocoa and 110 g sugar in a bowl.
Add milk, egg and melted butter to the dry ingredients and mix well with the whisks of the mixer (dough is very firm!). Fill the dough evenly into the forms and smooth it down.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Mix 4 tbsp. cocoa and 110 g sugar. Sprinkle approx. 2⁄3 of the cocoa-sugar mixture evenly onto the moulds. Pour 70 ml of boiling water evenly onto the dough of each mould.
Place on a baking tray and bake in a hot oven for 35-40 minutes. Remove and sprinkle with the remaining cocoa-sugar mix. Serve still warm. Vanilla ice cream tastes good with it.