1. Preheat your oven to 350 degrees F.
2. In a large mixing bowl, sift together the flour, baking soda, baking powder, and salt. Whisk until combined and set to the side.
   350 grams all-purpose flour, 6 grams baking soda, 4 grams baking powder, 3 grams salt

Brown Butter:

1. Heat a 12-inch cast iron skillet to medium heat and melt the butter.
   226 grams unsalted butter
2. Once the butter has completely melted, continue to cook the butter, stirring continuously, so it doesn't burn.
3. Remove the butter from the heat once it turns an amber color and you see small brown specks on the bottom of the pan.

Wet Ingredients:

1. Immediately, stir in the brown sugar and white sugar until combined.
   200 grams white sugar, 220 grams brown sugar
2. Allow for the butter and sugar mixture to cool slightly before adding in the beaten eggs. This will prevent scrambled eggs in your sourdough cookie dough!
3. In a separate bowl, whisk together the egg, egg yolk, sourdough discard and vanilla extract.
   1 large egg, 1 egg yolk, 8 grams vanilla extract, 140 grams sourdough discard
4. Once the mixture is cooled, add the egg mixture and stir until fully incorporated.

Dry Ingredients:

1. Pour the dry ingredients into the wet ingredients. Continue to mix until all of the flour mixture has been incorporated. This will take a minute or two.
2. Finally, fold the chocolate chunks into the sourdough cookie dough. I like to top the cookie batter with extra chocolate chips.

   Note: make sure that the cookie dough has cooled to room temperature. If it is still warm, the chocolate chips will melt while mixing.
   10 ounces chocolate chips or chunks
3. Use a wet paper towel to wipe away any extra flour bits on the sides of the cast iron skillet for a clean finished look.

Bake:

1. Place in a preheated oven and bake for 30-35 minutes or until the top is golden brown and the edges are just beginning to pull away from the skillet and look crispy.
2. Place on a cooling rack for 5 minutes before serving. Enjoy!