Sourdough Biscoff Blondies (with Browned Butter)
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Use up your sourdough discard and make these exceptional Sourdough Biscoff Blondies! They are chewy, soft, and packed with flavor thanks to the Biscoff cookie butter inside and drizzled over the top. Top with chopped white chocolate and crushed Biscoff cookies for the sweetest treat that bakes in under 30 minutes!
I love these so much I could cry. I’ve been craving Biscoff cookie butter all week, and I had some extra sourdough starter that I wasn’t going to bake bread with after all, so I knew this recipe had to be created.
Browning the butter is a step I highly recommend because it adds a gorgeous, nutty, caramel flavor to these sourdough blondies. But, if you’re short on time, just melt the butter and carry on (as long as you promise me next time you’ll brown the butter!).
Step-By-Step Instructions
Preheat oven to 350°F and line a 9×9 pan with parchment paper.
Brown the butter in a skillet over medium heat until golden and nutty-smelling. Let cool slightly.
Sift together the flour, baking powder, and salt. Set aside.
Whisk the browned butter and brown sugar until smooth. Add the cookie butter, eggs, and egg yolk. Whisk well.
Add the sourdough discard and vanilla. Whisk until smooth and fully combined.
Fold the dry ingredients into the wet ingredients using a spatula. Mix until just combined. Fold in half of the chopped white chocolate.
Spread the batter into the prepared pan. Top with remaining white chocolate. You can choose to add the crushed cookies now or wait until they come out of the oven.
I prefer the crunchiness of the cookie, so I add them after.
Bake for 25–28 minutes, until the edges are golden brown and the center is slightly soft.
Cool completely, then drizzle with melted cookie butter and slice into bars.
Helpful Tips for the Best Biscoff Blondies
- Brown the butter carefully. Once the milk solids turn golden brown and smell nutty, remove the pan from the heat immediately to avoid burning.
- Use room temperature eggs for a smoother batter and more even texture.
- Whisk the sourdough discard thoroughly into the wet ingredients so it fully incorporates without lumps.
- Sift the dry ingredients to help prevent overmixing and keep the blondies soft and tender.
- Mix the batter until just combined. Overmixing can create dense or cakey blondies instead of chewy, fudgy ones.
- Slightly underbake the blondies for the best texture. The center should still feel a little soft when removed from the oven — they will continue setting as they cool.
- Sprinkle extra white chocolate over the top before baking for melty pools of chocolate throughout the blondies.
- Warm the cookie butter slightly before drizzling so it spreads easily over the cooled blondies.
- Allow the blondies to cool completely before slicing for clean cuts and the perfect chewy texture.
- For extra flavor and crunch, press a few additional crushed Biscoff cookies onto the top right after baking.
Equipment Used
- 9×9-inch baking pan
- Parchment paper
- Cast iron skillet or saucepan
- Mixing bowls
- Whisk
- Silicone spatula
- Measuring cups and spoons
- Kitchen scale (optional, for metric measurements)
- Fine mesh sieve or sifter
- Knife and cutting board (for chopping chocolate)
Storage Instructions
These blondies also freeze well. Wrap individual bars tightly and freeze for up to 2 months. Thaw at room temperature or warm briefly in the microwave before enjoying.
Store the blondies in an airtight container at room temperature for up to 4 days.
For a softer, fudgier texture, warm individual blondies in the microwave for 10–15 seconds before serving.
To refrigerate, store in an airtight container for up to 1 week. Allow them to come to room temperature before serving for the best texture.
Looking for more blondie recipes? Check these out!
Sourdough Biscoff Blondies (with Browned Butter)
Ingredients
Dry Ingredients
- 1 cup all-purpose flour 120 g
- 1 teaspoon baking powder 4 g
- 1/2 teaspoon salt 3 g
Wet Ingredients
- 1/2 cup butter browned (113 g) I use salted. If using unsalted, add an additional 1/4 teaspoon salt
- 1 cup packed brown sugar 220 g
- 1/4 cup Biscoff cookie butter 60 g
- 2 large eggs room temperature
- 1 egg yolk
- 1/2 cup sourdough discard 120 g
- 1 teaspoon vanilla extract 5 g
Mix-Ins & Toppings
- 4 ounces white chocolate chopped and divided (113 g)
- 6 Biscoff cookies crushed
- Extra Biscoff cookie butter for drizzling
Instructions
- Preheat your oven to 350°F. Line a 9×9-inch baking pan with parchment paper and set aside.
Brown the Butter
- Brown the butter first. Add the butter to a cast iron skillet or saucepan over medium heat. As the butter melts, it will begin to foam and crackle. Stir frequently and watch closely. After several minutes, the milk solids at the bottom will turn golden brown and the butter will smell warm, nutty, and caramel-like. Remove from the heat immediately to prevent burning and allow it to cool slightly.
- If you're short on time, you can use melted butter instead!
Sift Dry Ingredients
- In a medium bowl, sift together the flour, baking powder, and salt. Set aside.
Mix the Wet Ingredients
- In a large mixing bowl, whisk together the browned butter and brown sugar until smooth.
- Add the Biscoff cookie butter, eggs, and egg yolk. Whisk until fully combined.
- Add the sourdough discard and vanilla extract. Whisk thoroughly until the discard is fully incorporated and the mixture is smooth.
Combine the Dry and Wet Ingredients
- Using a spatula, gently fold the dry ingredients into the wet ingredients until just combined. Do not overmix.
- Fold in half of the chopped white chocolate.
- Spread the batter evenly into the prepared baking pan. Sprinkle the remaining white chocolate over the top, followed by the crushed Biscoff cookies. I prefer to add the cookies after the blondies are done baking, because I like the crunch of the cookies on the blondies. Do whatever you prefer!
Bake the Blondies
- Bake for 25–28 minutes, or until the edges are golden brown and set. The center may still seem slightly underdone — this is completely normal for blondies. They continue to set as they cool, creating a soft, chewy, fudgy texture.
- Allow the blondies to cool completely before drizzling with extra melted Biscoff cookie butter (I microwave it for about 15-20 seconds) and slicing into squares.
Notes
Storage Instructions
- Store the blondies in an airtight container at room temperature for up to 4 days.
- For a softer, fudgier texture, warm individual blondies in the microwave for 10–15 seconds before serving.
- To refrigerate, store in an airtight container for up to 1 week. Allow them to come to room temperature before serving for the best texture.
- These blondies also freeze well. Wrap individual bars tightly and freeze for up to 2 months. Thaw at room temperature or warm briefly in the microwave before enjoying.
These sourdough blondies with Biscoff cookie butter and cookies are…ridiculous! Seriously, we loved them and I hope you do too. If you make them, I’d love to hear your thoughts!