Add sugars to a bowl.
Melt butter, allow to cool and then mix in the beaten egg yolks. Pour this in with sugar and mix well. Slowly add the dry ingredients and continue mixing. Finally stir in chocolate chips.
Roll into balls place onto baking tray covered with baking parchment. Bake for 15-17 mins or golden brown allow to cool on tray for couple minutes then move to cooling rack.