Sourdough Peanut Butter Swirl Brownies

Sourdough discard is always in abundance around here, so I’m always seeking out new ways to use it up rather than throwing it out. Thankfully there are endless varieties of recipes that call for sourdough discard. No shortage of options here!

I frequently use up any sourdough discard in pancakes, waffles, crepes, pizza crust, or even crackers. There really is no need to throw out any discard with so many possibilities.

Brownies are a fun movie night treat for any time of year, but wouldn’t it be nice if they were a bit healthier? Well, they can be! Sourdough makes any item that contains flour so much better than normal. Learn more about the health benefits of sourdough here.

Anyway, lets get to the good stuff!

Sourdough brownies are a healthier alternative to a classic dessert thanks to natural sweeteners like honey and the breakdown of flour by sourdough. Allow them to ferment overnight in order to receive all the benefits from fermentation, or whip them up right away. Quick, delicious, easy, and healthier…what’s not to love? Find the recipe and step-by-step instructions below! Oh, and there’s more information about sourdough at the end of this post if you’re interested in learning more about this nutrient-dense food. Enjoy!

How to Make Sourdough Brownies

What You’ll Need

  • 9×13 baking pan
  • 3 mixing bowls: 1 large, 1 medium, 1 small
  • Measuring cups and spoons
  • Small saucepan
  • Whisk
  • Spatula


Brownie Batter:

  • 1/2 cup of all purpose flour
  • 1/2 tsp of salt
  • 1/3 cup of unsweetened cocoa powder
  • 8 oz of semi-sweet chocolate chips
  • 1 and 1/4 cup of melted butter
  • 2 large eggs and 1 egg yolk
  • 1/2 cup of white sugar
  • 1/4 cup of maple syrup
  • 1/2 cup of sourdough discard
  • 1 TBS of vanilla

Peanut Butter Swirl (optional):

  • 3 TBS of peanut butter
  • 1 TBS of maple syrup

Keep in Mind: feel free to double the peanut butter swirl recipe if you’d like even more peanut butter flavor in the brownies!

Step-by-Step Instructions

  1. The night before, mix together the sourdough, flour, maple syrup, and melted butter. Cover the bowl and allow to ferment for 8-24 hours.
  2. The next day, preheat the oven to 350 degrees.
  3. Add the salt and cocoa powder to the sourdough mixture that you let ferment overnight. Combine well.
  4. In a medium saucepan, melt the chocolate chips over medium heat until smooth. Be sure to stir often.
  5. Take the chocolate off the burner after melted and allow to cool.
  6. In a medium bowl, whisk together the eggs and sugar. Proceed to combine this mixture with the sourdough mixture.
  7. Pour in the cooled chocolate and mix well until everything is evenly combined.
  8. Pour the brownie batter into a greased 9×13 pan.
  9. (Optional) Combine the peanut butter and vanilla to a small bowl, stir well, and drop even bits of the swirl into the brownie batter. Use a toothpick or fork to swirl around in a fun design.
  10. Bake for 25 minutes or until a toothpick comes out of the middle of the brownies with no residue on it.
  11. Allow the brownies to cool completely before slicing so they set nicely.
  12. Top with powdered sugar, serve with ice cream, or enjoy with a cold glass of milk.


  1. “Must I really longer ferment this recipe?” Nope! Just keep in mind that you will not receive the same health benefits of the fermentation process without long fermentation. The brownies will still taste great, but the flour in the recipe will not be broken down for easier digestion.
  2. “Is the peanut butter swirl necessary?” No it isn’t. Simply omit it from the recipe if it isn’t something you’d like to add! It will not take away from the overall flavor of the brownies.
  3. Make sure to allow the brownies to cool before cutting. This will help them stay together better!
  4. Sometimes dry clumps will form in the batter and can be tricky to break apart when mixing. I’ve found that pressing them against the side of the bowl with a fork does the trick!

If you make this recipe and love how it turned out, feel free to come back and comment about your experience. I’d love to see your creation and how you served it!

How to Store Them

Store in an air-tight container for up to 3 or 4 days. They last longer than that, but they become dry and crumbly.

Store in an air-tight container in the fridge for 5 to 7 days.

Wrap in wax paper, place in a storage bag, and freeze for up to 2 months.

Do I Have To Mix It Up The Day Before?

Nope! You can mix the dough up the same day you plan to bake the brownies. It won’t hurt anything. The only downside will be that the health benefits of long fermentation will not be as prevalent.

How Can I Make My Own Sourdough Starter?

Interested in implementing sourdough into your kitchen? Here’s everything you need to know to get your sourdough starter going.

All it takes is flour, water, and about 7 days time.

I also answer a few of the most frequently asked questions about sourdough over here.

How is Sourdough Healthier than Regular Bread?

Read more in depth about the health benefits of sourdough here. I explain four reasons that sourdough is one of the healthiest breads you can consume, as well as describe how the fermentation process of sourdough works.

Other Yummy Sourdough Recipes

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