Sourdough Peanut Butter Brownies

Fudgy, rich, and swirled with creamy peanut butter, these sourdough peanut butter brownies are the perfect way to use up sourdough discard in a decadent dessert. I've added a triple hit of peanut butter goodness, along with 120g of sourdough starter (or sourdough discard), so you can guarantee you're going to taste the peanut butter!

Speaking of peanut butter, if you love peanut butter without the chocolate, make sure you check out these sourdough peanut butter squares.

Why You'll Love This Recipe!

Deliciously Fudgy Texture – The sourdough discard adds moisture, making these brownies extra rich and gooey with a chewy bite.

Perfect Sweet-Salty Combo – The creamy peanut butter swirl balances the deep chocolate flavor with a nutty, savory contrast. And you can bet I've added a little salt to balance it all out!

Waste-Free Baking – It’s a tasty and creative way to use up sourdough discard instead of tossing it out (and if discard recipes are your jam, then check out this collection of 100+ sourdough discard recipes).

Ingredients

• All-Purpose Flour – Provides structure to the brownies and helps balance the moisture from the sourdough starter and peanut butter.
• White Sugar – Sweetens the brownies and helps create a slightly crisp top layer ... and did I mention those crispy edges?
• Cocoa Powder – Adds rich chocolate flavor and pairs well with the tangy undertones from the sourdough. I've just used supermarket brand cocoa powder, but you can use fancier cocoa powder if you prefer.
• Salt – Enhances the chocolate and peanut butter flavors and balances the sweetness.
• Baking Powder – Gives the brownies a slight lift for a softer texture without making them too cakey, but measure carefully as you want to keep the fudgey texture and too much baking powder will give you cakey brownies!
• Chocolate Chips (I've used semi-sweet) – Melt slightly into the batter for pockets of gooey chocolate, balancing sweetness and depth.
• Peanut Butter Chips – I've used Reese's to an extra layer of creamy peanut butter throughout the brownies. You can replace these with white chocolate if you prefer.
• Butter (melted) – Gives the brownies a rich, fudgy texture and blends smoothly with the other ingredients. I've used salted butter.
• Peanut Butter – I've used natural, unsalted, unsweetened crunchy peanut butter. You can use smooth if you prefer.
• Eggs - I've used large eggs from my backyard chickens. I recommend using 3 eggs if yours are on the small side.
• Vanilla Extract – Adds warmth and depth to both the chocolate and peanut butter flavors.
• Sourdough Starter - You can use active sourdough starter or discard, whatever you have on hand is perfectly fine.

How To Make Sourdough Peanut Butter Brownies

This recipe for sourdough peanut butter brownies is based on my tried and tested sourdough brownie recipe. It's so good and was just begging to be turned into peanut butter brownies!

Preheat the oven to 160C/320F. Grab a 9" x 9" brownie pan - it's up to you whether you grease the pan with butter or line it with parchment paper.

In a bowl, add the all purpose flour, white sugar, cocoa powder, peanut butter chips, chocolate chips, salt and baking powder. Whisk the dry ingredients together until well combined, ensuring the chocolate and peanut butter chips are well distributed. Set this bowl aside for now.

In a separate bowl, add the peanut butter and melted butter together and stir until well combined (see notes for how I do this easily).Into the same bowl, add the 2 eggs and vanilla extract and whisk until thick and creamy. Then add the sourdough starter and whisk again until well combined.

Pour the liquid ingredients on top of the dry ingredients and use a spatula to bring them together into a thick brownie batter. You only need to moisten the dry ingredients, don't be tempted to over mix the batter.

Place the sourdough brownie mixture into your prepared pan and use a spatula to spread it to the edges. Dollop peanut butter on top of the brownie mixture and use a skewer to toothpick to swirl it into the brownie batter.

Place the pan into the oven and bake for 35 minutes at 160C/320F.

Check the sourdough peanut butter brownies at 35 minutes by inserting a tooth pick - you want it to come out wet still but they should be crackly and baked on top.

Remove from the oven and allow to cool in the pan for around 30 minutes. Then remove from the pan and allow to cool completely on a wire rack before slicing into squares.

How to Store + Freeze

Sourdough peanut butter brownies will last for around 7 days in an airtight container. I've had better luck keeping them in a tin lined with parchment paper than plastic.

You can freeze them. Wrap in parchment paper and then in tin foil and freeze. It's better to freeze them as a whole "cake" rather than cut before freezing.

To defrost, allow them to sit on the counter until thawed through. Warm slightly before serving (microwave is fine).

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