Put butter and sugar in a bowl and mix together.
Add the egg and mix well.
Sift cake flour, baking powder, and salt into the bowl and combine.
Add chocolate chips, nuts, or other mix-ins of your choice and stir evenly.
Shape the dough into balls and place them on a baking tray.
Bake in a preheated oven at 180°C for 12-15 minutes.
Cool the cookies and they're ready to serve.