Preheat the oven to 180°C.
Place the butter and sugar in a saucepan to soften. Remove from the heat and mix in the baking powder.
Mix together the flour and the cocoa powder and then form a well in the centre. Break the eggs into the well and then whisk in the milk and the butter/sugar mixture a little at a time.
Beat the egg whites to stiff peaks. Fold a third of the egg whites into the flour, butter and egg mixture. Mix well and then fold in the remanining egg whites. Carefully fold in the chocolate chips.
Pour the mixture into muffin moulds, transfer to the oven and bake for 20 minutes.
Allow to cool on a baking rack before serving.
«Vary this recipe by adding white chocolate chips, pecan nuts or fresh berries.»