Place the dry ingredients (all purpose flour, baking soda corn starch, salt, chocolate chips, pecans and spices) into a large mixing bowl and combine. Set this aside.
Now in a separate bowl, combine the sourdough discard or sourdough starter, melted butter, brown sugar, white sugar, egg + egg yolk and vanilla extract. Stir together until they resemble runny caramel.
Now pour the wet ingredients into the dry ingredients and stir to form the cookie dough.
Cover the bowl and place the dough in the fridge for at least 2 hours, but up to 24 hours.
When you are ready to bake the sourdough cookies, preheat the oven to 175C (350F) and cover 2 large cookie sheets with parchment paper.
Scoop out balls of cookie dough using a cookie scoop (my cookie dough balls weigh around 30g each). Place the cookie dough balls onto your parchment lined cookie sheets and gently press each ball down using the bottom of a measuring cup.
Bake the sourdough cookies for around 15 minutes at 175C or 350F. I like to remove the sourdough cookies from the oven when the middle is still a bit soft and gooey, but the edges are crispy and golden.
Allow the sourdough cookies to cool on the tray for 10 minutes before carefully removing to a wire rack to finish cooling.