In a medium bowl, whisk together the gluten-free flour, sorghum flour, xanthan gum, salt, and baking soda until combined. Set aside.

Add the butter, shortening, granulated sugar, and brown sugar to the bowl of a stand mixer. Mix on medium-low speed until combined. Scrape down the bowl and add the egg and vanilla extract and mix well. Add the sourdough discard and mix until completely incorporated.

Pour in the flour and mix on low speed until the dry ingredients are combined. Turn off the mixer and add the chocolate chips, stirring them in by hand.

Form the dough into one large ball in the bottom of the bowl then cover the bowl with plastic wrap and chill for at least 6 hours (or up to 72 hours).

After the dough has chilled, preheat oven to 350 degrees and line 2 baking sheets with parchment paper or silicone baking mats.

Once the oven has preheated, scoop the dough out and form into 24 even-sized balls of cookie dough (I use a large OXO scoop).

Bake the cookies in batches of 6-8 per sheet on the center rack for 8-12 minutes. Once done, cool the cookies on the baking sheet for 10 minutes before removing and cooling on a wire rack.