Moist and Fudgy Sourdough Brookies

These sourdough brookies are the perfect mashup of fudgy brownies and soft chocolate chip cookies in one bite. The sourdough starter deepens the flavor without overpowering the classic, sweet combo. If you’ve got extra discard and a sweet tooth, this is your next favorite recipe.

These are straightforward, no mixer needed, and the ingredients are all pantry basics. You’ll mix two quick batters: one cookie, one brownie, and layer them for that marbled look. There’s no long ferment or resting time, but if you want a deeper sourdough flavor, chilling the dough overnight works too. They bake in under an hour and slice up clean once cooled.

What You’ll Need

Just simple pantry ingredients!

Cookie Dough

• ½ cup unsalted butter, melted
• ½ cup granulated sugar
• ½ cup brown sugar
• 1 egg
• 1 teaspoon vanilla extract
• ¼ cup sourdough starter (unfed, discard) use room temperature and stirred down for best results
• 1 teaspoon baking powder
• ¾ teaspoon salt
• 1 cup all-purpose flour
• 1 cup chocolate chips

Brownie Batter

• ½ cup vegetable oil (you can sub this for grapeseed, light olive oil, or avocado oil
• ¼ cup granulated sugar
• ½ cup brown sugar
• 2 eggs
• ¼ cup sourdough starter (unfed, discard)
• 1 teaspoon vanilla extract
• ½ cup all-purpose flour
• ⅓ cup cocoa powder
• ¼ teaspoon salt
• ½ cup chocolate chips

If you’d like to double or triple this recipe, you can make adjustments in the recipe card at the bottom of this post.

How to Make Sourdough Brookies

This recipe is written for an 8×8-inch pan, but a 9×9 will also work with slightly thinner layers and a shorter bake time (start checking around 38 minutes).

For a crowd, you can double the recipe and bake it in a 9×13 pan: just extend the bake time as needed, usually around 50–55 minutes.

Prep your pan and oven

Preheat your oven to 350°F and line an 8×8-inch baking pan with parchment paper.

A little baking spray under the parchment helps it stay in place while you layer the batter.

If you’re using a metal pan, you’ll get slightly crispier edges; glass or ceramic will bake a bit softer but still work just fine.

Make the cookie dough

In a large bowl, whisk together the melted butter, granulated sugar, and brown sugar until smooth and glossy. Add the egg, vanilla extract, and sourdough discard and whisk again until fully combined.

The discard should be room temperature and stirred down so you get an accurate measurement.

Switch to a spatula and add the flour, baking powder, and salt. Stir just until no dry spots remain, then fold in the chocolate chips. The dough will be soft and slightly sticky.

If you want more distinct layers, you can chill this while making the brownie batter, but it’s not necessary.

Make the brownie batter

In a separate bowl, whisk together the oil, granulated sugar, and brown sugar until well blended. Add the eggs, vanilla, and sourdough discard and mix until the batter is smooth and thick.

Stir in the flour, cocoa powder, and salt using a spatula. Fold in the chocolate chips last. This batter will be thinner than the cookie dough and should spread easily in the pan.

Layer the batters

Spoon half of the brownie batter into the prepared pan and smooth it into an even layer.

Use a cookie scoop or spoons to drop half the cookie dough over the brownie layer, spacing the scoops out a bit.

Add the rest of the brownie batter, then finish with the remaining cookie dough in the same scattered pattern.

Use a spatula to gently spread and level the top.

You don’t need to swirl the batters! Just press and smooth them so they bake up evenly with a nice marbled top.

Bake

Place the pan in the center of the oven and bake for about 45 minutes.

The brookies are done when a toothpick inserted in the center comes out with a few moist crumbs but no wet batter. The top will look set and lightly crackled.

Cool and slice

Let the brookies cool in the pan for about 10 minutes, then lift them out using the parchment paper and transfer to a wire rack. They’ll cut much more cleanly once they’re fully cool.

If you’re after bakery-style edges, you can chill the brookies before slicing. Cut into 16 squares and enjoy right away or store for later.

Leftovers will keep in an airtight container at room temperature for 3 days, or can be frozen up to 3 months.

Printable Recipe