Heated the oven. Sift the flour, baking soda and salt. In a separate bowl mix the butter, brown and white sugar. Stir well and add the vanilla, egg and yolk. Stir again become creamy. Mix dry and liquid mixture and mix nice. Add chocolate and stirring with a wooden spoon. You can add and nuts. I put on trays last few walnuts. Arrange on a tray littered with baking paper and bake in a preheated 180C oven until browned.