Place softened butter in a bowl and whip until smooth. Add sugar and salt, and mix well.

Once the sugar is less grainy, add the egg and mix thoroughly.

Sift the dry ingredients and fold them into the mixture using a spatula.

Add chocolate chips and walnuts, and gently mix until evenly distributed.

Cover the dough with plastic wrap and refrigerate for 1–2 hours.

Shape the dough into 40g balls and place them on a baking tray. Bake in a preheated oven at 180°C for 11–12 minutes.