Feed your sourdough starter at least 4-12 hours before starting the cookies.
In a stand mixer bowl, add brown sugar, sugar, and butter, and beat with the paddle attachment until pale in color.
Add in egg, vanilla, and sourdough starter. Mix until combined.
In a separate bowl, mix together dry ingredients.
While the mixer is on low, add in dry ingredients about 1/3 at a time until the dough forms. Don't over mix, or you will have tough cookies.
Mix in chocolate chips.
To make them right away: Spoon onto parchment lined baking sheet and bake at 350 degrees for about 15-20 minutes, or until they start to turn golden brown around the edges.
To Long Ferment:
Place dough into a large bowl, add a lid, and place in the refrigerator for 72 hours.
Preheat oven to 350.
Spoon your fermented dough onto a parchment-lined baking sheet and bake at 350 degrees for about 15-20, minutes or until they start to turn golden brown.
Move to a cooling rack to cool. Enjoy.
Notes
For most flavor and best digestibility, ferment the dough in the refrigerator for 3 days.