Preheat the oven to 350°F and line baking sheets with parchment.
This cookie dough can be mixed by hand or with an electric mixer.
In a small mixing bowl thoroughly whisk the flour, cocoa powder, xanthan gum, baking soda and salt.
In a medium sized mixing bowl, cream the butter and sugar together until smooth.
Add the egg yolks, milk and vanilla and beat until smooth.
Add the dry ingredients in 2 additions and mix until combined.
Stir in the chocolate chips by hand.
Drop about 2 Tbsps dough per cookie onto the baking sheet.
For cookies that don't spread and stay softer, chill the dough (portioned cookie dough on the pan) in the refrigerator for at least 30 minutes.
Bake 8-10 minutes. Cool on the pan for 5 minutes, then transfer to a wire rack to cool completely.