Preheat the oven to 180°C.
Cream together the butter and sugar.
Add the egg and mix.
Sift in flour, cocoa powder, baking powder, and salt.
Add chocolate chips and mix to form a dough.
Shape the dough into balls and place them on the baking tray.
Bake in the oven for 12 to 15 minutes.
Cool on a wire rack.