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.

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
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4.62 from 80 reviews

Sourdough Blondies

Butterscotch blondies get a boost of flavor from sourdough discard. These blondies are both gooey and light at the same time.
Prep Time20 minutes
Bake Time30 minutes
Total Time50 minutes
24 blondies
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  • 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


  • 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.

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I like to use a very ripe discard in this recipe, one that hasn’t been fed for at least a week.
The recipe can  be halved and baked in a 9×9 square pan.


Serving: 1square | Calories: 285kcal | Carbohydrates: 41g | Protein: 3g | Fat: 12g | Saturated Fat: 8g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 3g | Trans Fat: 0.5g | Cholesterol: 58mg | Sodium: 69mg | Potassium: 68mg | Fiber: 0.5g | Sugar: 28g | Vitamin A: 394IU | Calcium: 33mg | Iron: 1mg
Have you tried this recipe?Mention @eileen.bakingsense or tag #bakingsense!

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Recipe Rating


  1. I just made these and they turned out amazing! So happy to have a new recipe to use for my sourdough discard!

    Thank you! 🙂

  2. 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.

  3. 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!!

    1. 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.

    1. 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.

  4. My second batch is now in the oven. The first batch, from a few weeks ago was incredibly nice. This time I am approaching it from a ‘lockdown’ perspective, and have used coconut cream (leftover from making curry) instead of butter; it smells amazing, even before going into the oven 🙂

  5. I just whipped up a batch of these to use my first sourdough discard. My family loves them (and they’re VERY hard to please.) The blondies were right in the sweet spot between being not sweet enough for my daughter or too sweet for my husband.

    They turned out less dense than I expected and the lightness was greatly appreciated.

    It’s nice to know that I can make a pan of these anytime I have too much sourdough to deal with.

    1. I also had this problem. They never got done. My discard was from a week ago and should have worked. The toothpick test came out clean. But they are basically raw. I baked them for 38 minutes to get to that point. I let them cool, cut into them, and found them to be oozing. So I put them back in for another 15 but it didn’t help. What are we missing here?

  6. Hi,
    Thanks for sharing this recipe. Unlike one of your followers, mine turned out very gooey. Thought I was at the 30 minute mark, and did the toothpick as recommended. Oh well.
    Thanks for the vigorous egg to crust tip. Been waiting for that trick my entire baking life!
    I will make this again.

  7. Hi! I made these last night. The flavor is good but they turned out cakey. That’s not how I thought the consistency would be. Any tips?

    1. I usually think of “cakey” blondies as having a drier crumb, like a cake. Is that what you got or was the crumb buttery? If your starter was still quite active you might get a lighter crumb but they should still be quite rich.