Skip to Content

Sourdough Blondies

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.

three butterscotch blondies on a plate sprinkled with sugar

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:

three process shots showing how to mix sourdough blondie batter
Vigorously stir the eggs in to the batter, then fold the discard into the batter until it’s almost combined.
two images showing how to fold flour into sourdough blondies
Fold the flour into the batter
two photos showing sourdough blondies before and after baking
Line the baking pan with parchment to make it easy to lift the blondies out of the pan.

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.

a plate with three sourdough blondies

Sourdough Blondies

Yield: 24 blondies
Prep Time: 20 minutes
Bake Time: 30 minutes
Total Time: 50 minutes

Butterscotch blondies get a boost of flavor from sourdough discard. These blondies are both gooey and light at the same time.


  • 3 sticks (12 oz, 336g) unsalted butter, melted
  • 3 cups (24 oz, 672g) light brown sugar
  • 4 large eggs
  • 1 1/2 tablespoons vanilla extract
  • 1 cup (8 oz, 224g) sourdough discard (100% hydration)
  • 2 1/2 cups (12.5 oz, 350g) all purpose flour
  • 1/2 teaspoon table salt


  1. 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.
  2. In a large bowl, combine the melted butter and brown sugar. Add the eggs and vanilla, stir until combined then vigorously stir for 30 seconds. Fold in the sourdough discard. Stir in the the flour and salt. Spread the batter into the pan.
  3. Bake until the center springs back when lightly pressed and a toothpick inserted in the center comes out with wet crumbs, about 30 minutes.
  4. Cool to room temperature before removing from the pan and cutting into 24 pieces.


I like to use a very ripe discard in this recipe, one that hasn't been fed for at least a week.

Did you make this recipe?

Please leave a comment on the blog or share a photo on Instagram

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! :)


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.


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.


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.


Friday 6th of August 2021

Hi, I was wondering if I decrease the sugar content, will it totally change the texture of the blondies?


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.

Skip to Recipe