Place gluten free flour, xanthan gum, bicarbonate of soda and salt in a medium bowl; mix well.
USe an electric food mixer to whisk cream cheese and melted butter together. Add brown sugar and caster sugar; mix for 2 minutes on medium speed. Add vanilla extract and egg yolks; mix well.
Slowly add the dry flour mixture, mixing on low speed until well combined. Stir in chocolate chips.
Cover the mix with cling film and chill in the fridge for at least 2 hours.
Preheat oven to 190 C / Gas 5. Line a baking tray with baking parchment.
Remove cookie dough from fridge; let it stand at room temperature for 30 minutes.
Scoop 1 heaped tablespoon of cookie dough and place on prepared baking tray. Repeat with remaining mixture, placing the cookies 2cm apart as they will spread while they cook.
Bake cookies for 11-13 minutes. They might look under baked but they will finish cooking while cooling. Remove from oven and let them sit for 3 minutes before transferring to a wire rack to cool completely.