Preheat the oven to 200°C.
In a bowl, mix the butter and sugar together.
Add the egg and mix well.
Sift in cake flour, baking powder, and salt, then mix.
Add chocolate chips and walnuts and finish the dough.
Take large portions of dough, shape them into balls, and place them on a baking tray.
Bake in a 200°C oven for 12–15 minutes.