A delicious recipe for Sourdough Chocolate Chip Cookie Bars made in a 9x13-inch baking pan. You'll have crispy edges and a softer center: perfect for everyone to choose their favorite cookie piece!
Preheat the oven to 350℉ (175℃) and line a 9x13-inch baking pan with parchment paper (this is optional, but makes it easier to remove the cookie bars after baking). Set aside.
In a medium bowl, whisk together flour, salt, baking soda, cornstarch, and baking powder. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment (or in a large mixing bowl with a hand-held mixer), cream the butter and sugars until light and fluffy, 2-3 minutes.
Add the egg, vanilla extract, and sourdough discard and mix on low until smooth and combined.
Add the flour mixture and mix on low until combined. Stir in the chocolate chips until combined.
Using a large cookie scoop or spoon, roughly scoop the cookie dough into the prepared 9x13-inch baking pan. Use your hands or a spatula to evenly press the cookie dough to the edges of the pan and fill any spaces. This doesn't need to be too precise - the dough will rise and spread as it bakes, filling in any small gaps or rough spots!
Bake for 30-35 minutes until browned and the cookie bars are set on the edges. Let cool in the baking pan for at least 10 minutes before transferring to a cooling rack to cool fully. Slice into bars, then serve!
Notes
To make this recipe with active sourdough starter, replace the sourdough discard with active starter (200g). You do not need to make any other changes to the recipe. Looking for a classic cookie? Try these Sourdough Discard Chocolate Chip Cookies.