Preheat the oven to 180°C (356°F).
Coarsely chop the walnuts.
Mix butter and sugar until smooth.
Add the egg and mix well.
Sift together flour, baking powder, and salt, then mix into the batter.
Add chocolate chips and chopped walnuts and mix evenly.
Scoop the dough into desired portions and place on a baking pan.
Bake in the oven at 180°C (356°F) for 12–15 minutes.