Preheat the oven to 180°C (356°F).
Cream the butter and sugar together until smooth.
Add the egg and mix well.
Sift in the flour and baking powder, then knead the dough.
Add chocolate chips and mix.
Shape the dough into balls and place them on a baking tray.
Bake in the 180°C (356°F) oven for 12 minutes.
Cool on a wire rack.