Sourdough Chocolate Chip Cookie Bars

• Prep Time: 20 minutes (plus 1 hour chilling)

• Cook Time: 25-30 minutes

• Total Time: 1 hour 45 minutes (including chill time)

• Skill Level: Beginner

• Yield: One 9×13 inch pan, about 24 bars

Ingredients

For the Cookie Bars:

• 1 cup (2 sticks / 226g) unsalted butter, softened to room temperature

• 1 cup (200g) light brown sugar, packed

• ½ cup (100g) granulated sugar

• ½ cup (120g) unfed sourdough starter (100% hydration)

• 2 large eggs, at room temperature

• 2 teaspoons pure vanilla extract

• 2 ½ cups (312g) all-purpose flour

• 1 teaspoon baking soda

• 1 teaspoon fine sea salt

• 2 cups (340g) semi-sweet chocolate chips

Optional Add-in:

• 1 cup (125g) chopped walnuts or pecans for added crunch

Essential Equipment

• 9×13 inch baking pan

• Parchment paper

• Electric hand mixer or stand mixer

• Large mixing bowl

• Medium mixing bowl

• Whisk

• Spatula

Step-by-Step Instructions

Step 1: Prepare the Pan and Preheat Oven

Grease your 9×13 inch baking pan and line it with parchment paper, leaving an overhang on the two long sides. This “sling” will make it incredibly easy to lift the entire slab of cookie bars out of the pan for clean cutting later. Preheat your oven to 350°F (175°C).

Step 2: Cream the Butter and Sugars

In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl using a hand mixer, cream together the softened butter, brown sugar, and granulated sugar. Beat on medium-high speed for 2-3 minutes, until the mixture is light, fluffy, and pale in color. This step is crucial for creating a tender texture and is the foundation of your cookie bars.

Step 3: Incorporate the Wet Ingredients

Reduce the mixer speed to low and add the sourdough starter, eggs, and vanilla extract. Mix until just combined. The mixture may look slightly curdled—this is perfectly normal and will come together once you add the dry ingredients.

Step 4: Combine the Dry Ingredients

In a separate medium bowl, whisk together the all-purpose flour, baking soda, and salt. This ensures the leavening agent and salt are evenly distributed throughout the flour, preventing any bitter pockets in the final bars.

Step 5: Bring the Dough Together

With the mixer on low speed, gradually add the dry ingredients to the wet ingredients. Mix only until the last streaks of flour disappear. Be careful not to overmix! Overmixing develops gluten, which can lead to tough cookie bars.

Step 6: Fold in the Chocolate

Switch to a spatula for this final step. Add the chocolate chips (and nuts, if using) and fold them gently into the dough until they are evenly distributed.

Step 7: Chill the Dough (The Secret to Perfect Bars)

This is a non-negotiable step for the best results. Press the dough evenly into your prepared baking pan. Cover the pan with plastic wrap and refrigerate for at least 1 hour. Why chill?

• Prevents Over-Spreading: It solidifies the butter, so the bars bake up thick and chewy instead of thin and crispy.

• Enhances Flavor: It allows the flour to fully hydrate and the flavors to meld and deepen.

Step 8: Bake to Perfection

Once chilled, place the pan in the preheated 350°F (175°C) oven. Bake for 25-30 minutes. The bars are done when the top is light golden brown and the edges are pulling away from the sides of the pan. The center should still look slightly soft and underbaked—a toothpick inserted will not come out clean, and that’s what you want! This residual heat will continue to cook the center as it cools, yielding a fantastically soft and gooey texture.

Step 9: Cool Completely

This is the hardest part—waiting! Allow the cookie bars to cool completely in the pan set on a wire rack. This will take at least 1-2 hours. For the cleanest cuts, you can even refrigerate the cooled pan for an additional 30 minutes before slicing.

Storage and Shelf Life

These Sourdough Chocolate Chip Cookie Bars store beautifully, making them a fantastic make-ahead treat.

• Room Temperature: Store in an airtight container at room temperature for up to 4 days.

• Refrigerator: They will keep for up to a week in the refrigerator. The cool temperature gives them a delightful fudge-like texture.

• Freezer: For longer storage, you can freeze the baked and cooled bars for up to 3 months. Wrap individual bars in plastic wrap and place them in a freezer bag. Thaw at room temperature or warm gently in the microwave.

Nutrition Information

Please note that the following is an estimate based on the ingredients used and will vary depending on specific brands and portion sizes. This information is provided as a courtesy.

Serving Size: 1 bar (1/24 of recipe)
Calories: ~315
Total Fat: 16g

• Saturated Fat: 9g
  Cholesterol: 35mg
  Sodium: 180mg
  Total Carbohydrates: 42g

• Dietary Fiber: 2g

• Sugars: 27g
  Protein: 4g

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There you have it—the ultimate fusion of classic comfort and sourdough sophistication. These Sourdough Chocolate Chip Cookie Bars are sure to become a new favorite, impressing both sourdough enthusiasts and cookie purists alike. The deep, complex flavor and unbeatable chewy texture are a testament to the magic that happens when tradition meets innovation in the baking dish. Happy baking