Sourdough Blondies! The perfect gooey blondie with a crackly crust is made even better with a dash of sourdough discard. These blondies have amazing butterscotch flavor.

These blondies are nice and rich, but with a surprisingly light crumb thanks to a little lift from the natural yeast in the sourdough starter.
But wait, there’s more…
The discard also enhances the flavor of the blondie. There’s a slight background tang that is the perfect counterpart to the sweet butterscotch flavor. It’s so, so good.
If you don’t have one, check out my post to learn How to Make a Sourdough Starter. Then check out my system to Feed and Maintain Sourdough Starter or How to Keep a Small Starter.
Scroll through the step by step photos to see how to make Sourdough Blondies:



Tips for making and storing Sourdough Blondies:
- The recipe can be halved and baked in an 8″ or 9″ square pan.
- Unfed sourdough starter will add a tangy flavor to the batter. I got great results with a starter that had been in the refrigerator, unfed, for about a week.
- Butter the pan and line with parchment paper. This not only prevents sticking, it makes it much easier to lift the blondies out of the pan.
- Stirring the batter vigorously after adding the eggs will incorporate air into the batter. As the blondies bake the bubbles rise to the surface and help form the crust. If you prefer a soft top on your blondies, you can skip that step.
- Cool the blondies in the pan then use the parchment to transfer them to a cutting board.
- To appreciate the subtle tangy flavor, I prefer to serve these spectacular blondies without any frosting
- The blondies will keep at room temperature for several days.
- Leftover blondies can be frozen. Layer them with parchment paper or plastic wrap to prevent them from sticking together. They’re delicious straight from the freezer or defrosted.
You might also like these other Blondie recipes, Classic Blondies, Butterscotch Ripple Blondies and Malted Milk Blondies.
For you chocoholics I’ve got lots of recipes for the blondies’ cousin: Fudgy Brownies, Sourdough Brownies, Habanero Brownies, Chocolate Cherry Brownies, Malted Milk Brownies, Roasted Beet Brownies, and White Chocolate Raspberry Brownies.


Since you’ve got your starter fed, peruse the entire list of My Best Sourdough Recipes. Have fun!
I know you hate to throw away that sourdough discard. Check out these recipes that use sourdough discard.
You might also want to try Sourdough Shortbread or Sourdough Chocolate Chip Cookies made with sourdough powder.
If you love this recipe as much as I do, I’d really appreciate a 5-star review.
Sourdough Blondies
Ingredients
- 12 oz unsalted butter (melted)
- 24 oz brown sugar (3 cups)
- 4 large eggs
- 1 ½ tablespoons vanilla extract
- 8 oz sourdough discard (1 cup)
- 12 ½ oz all purpose flour (2 ½ cups)
- ½ teaspoon table salt
Instructions
- Preheat the oven to 375 °F. Butter a 13" x 9" baking pan and line with parchment paper. You can just butter the pan but the parchment makes it much easier to remove the blondies from the pan.
- In a large bowl, combine 12 oz unsalted butter and 24 oz brown sugar. Add4 large eggs and 1 ½ tablespoons vanilla extract, stir until combined then vigorously stir for 30 seconds. Fold in 8 oz sourdough discard. Stir in 12 ½ oz all purpose flour and ½ teaspoon table salt. Spread the batter into the pan.
- Bake until the center springs back when lightly pressed and a toothpick inserted in the center comes out with wet crumbs, about 30 minutes.
- Cool to room temperature before removing from the pan and cutting into 24 pieces.
Equipment
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Rachel Hubach
Friday 27th of May 2022
I just made these and they turned out amazing! So happy to have a new recipe to use for my sourdough discard!
Thank you! :)
Ks
Thursday 7th of October 2021
Can i use dry active yeast to substitute the sourdough? And what is the instructions?
Eileen Gray
Friday 8th of October 2021
No need for yeast. The starter is there for flavor, mostly. You can make blondies without the starter.
Jan
Tuesday 21st of September 2021
Made these tonight with my discard! Love love love! Will definitely make these again. I used vanilla sea salt for the salt and it was fab. Thanks for the discard recipes! Hate throwing away.
Amanda
Friday 10th of September 2021
I love this recipe! I've made it a couple times now, and the flavor is always perfect! It has a not-too-sweet, slightly tangy flavor. The only thing is I can never get the baking time right. 30 minutes and it is still very raw.. I like mine gooey, but not liquidy :). I think somewhere between the 40-45 min bake time it usually turns out good for me. This last batch I baked for about 43 minutes and I almost whished I would have taken it out a little sooner to get it a little more gooey. The edges cook much faster than the middle, so just be aware of that. Overall, LOVE the flavor!! Thank you for the recipe!!
Eileen Gray
Friday 10th of September 2021
Glad you like the recipe Amanda. I love the way the tangy sourdough discard heightens the flavor of the blondie. The baking time will vary based on your real oven temp (mine often runs a little hot), the temp of the batter and the color and material of your baking pan.
Jen
Friday 6th of August 2021
Hi, I was wondering if I decrease the sugar content, will it totally change the texture of the blondies?
Jen
Friday 6th of August 2021
@Eileen Gray, thank you!!
Eileen Gray
Friday 6th of August 2021
Yes. Depending how much you reduce the sugar it will change the texture. You'd have to gradually decrease to see how low you can go before you don't like the result.