These peanut butter swirl brownies are truly decadent and rich in every bite. They’re the ultimate fudgy dark chocolate brownies swirled with salty, creamy peanut butter on top!

Peanut Butter Swirl Brownies | katiebirdbakes

This post is sponsored by Bob’s Red Mill and Bake from Scratch Magazine as part of their Better Baking Academy – but the opinions (and many devoured brownies during the testing process) are all mine.

Hello hello! We’re making super fudgy brownies today!

And not just any brownies. Peanut butter swirl brownies…oh yes. If you could pick my two favorite flavors in the world and bring them together, you would have peanut butter and dark chocolate…and these peanut butter swirl brownies would be the result.

Peanut Butter Swirl Brownies | katiebirdbakes

Peanut Butter Swirl Brownies: Details

I’m so excited to share a peanut butter brownie recipe with you as my interpretation of this month’s Better Baking Academy recipe – The Ultimate Brownie. The Better Baking Academy is a totally free, online baking school developed by Bob’s Red Mill and Bake from Scratch Magazine. Each month they will release a new recipe focusing on fundamental baking skills, with with step-by-step photos and expert tips.

When Bob’s and Bake from Scratch reached out to me to play with their new recipe for The Ultimate Brownie, it was a no-brainer. I already have a few brownie recipes on here, including a flourless skillet brownie and my favorite fudgy brownies, but seriously, you can never have enough brownie recipes in your life.

If you want to hear me talk about all things brownies, chocolate, how I learned to bake and my double life as an attorney and blogger, I’ll be appearing this week on The Crumb Podcast with Brian Hart Hoffman and Kyle Grace Mills from the Bake from Scratch editorial team. I had so much fun talking to them about this peanut butter swirl brownie recipe and love their passion for baking! You can listen to it anywhere you get your podcasts.

Peanut Butter Swirl Brownies | katiebirdbakes

Brownies are my go-to for any party, birthday, breakup, bad day, good day, and random Tuesday. They make everyone light up and never fail to satisfy that chocolate craving at the end of a meal…if they’re done correctly.

Unfortunately, there are way too many subpar brownie recipes out there. And let’s not even talk about the fact that most people rely on brownie mixes to do the job…some people don’t even think it’s possible to make a homemade fudgy brownie without a box mix.

Well I am here to say: false.

Peanut Butter Swirl Brownies | katiebirdbakes

Tips for success: homemade fudgy peanut butter brownies

You can read the Better Baking Academy post for more detail on this, but for me after much trial and error, it comes down to the following:

  1. Melted, good quality chocolate. This adds moisture, flavor, fat, and that amazing mouthfeel we all crave. I like to use a dark chocolate with at least 60% cocoa for best flavor. In this recipe we are melting the butter and chocolate together for fudgiest results.
  2. Eggs. The proteins provide structure to the brownie as it bakes, but also richness and fat from the yolk. Often you’ll see recipes add an extra egg yolk for even more richness (it’s not needed here).
  3. Slightly under-baking. Anyone who has baked a box mix knows this, but if you bake brownies just a couple minutes under the recommendation, the fudge factor is massively higher. Don’t worry, everything is fully cooked by the time we take them out.
  4. Refrigeration. This was a new technique to me with this recipe, but it really works! After letting the pan cool for a couple minutes, we put the entire thing in the fridge (sitting on a tea towel to protect the shelf) until cold, and once cut, we store the brownies covered in the fridge too. It keeps the brownies from drying out and losing their richness.

How to make a peanut butter swirl on brownies

Now, let’s talk about the final element: the peanut butter on these peanut butter swirl brownies.

Peanut Butter Swirl Brownies | katiebirdbakes

Is there a better pair than peanut butter and chocolate? I really don’t think so. But there’s definitely a limit to how much peanut butter one can use for the right balance.

I personally don’t want huge mouthfuls of peanut butter in my fudgy brownie, so I kept it to a thin swirl sitting on top of the batter. I used just 1/4 cup of room temperature, unsweetened, natural creamy salted peanut butter (the kind with just peanuts and salt as the ingredients – Trader Joe’s, Whole Foods, and most major grocery stores all have great versions).

You can also use shelf-stable peanut butter if you prefer. I tested with Skippy Natural and it definitely still worked, but because it has a thicker, less liquid texture, it didn’t swirl quite as prettily.

Peanut Butter Swirl Brownies | katiebirdbakes

My best tip to getting a good pattern with the swirl is to dollop the peanut butter evenly in very small spoonfuls over top, then use a toothpick to randomly swirl it around. Don’t do it in a uniform way; rustic is best here. See the video for this post for my *highly scientific* swirling technique (haha).

For the cleanest cuts on the brownies, make sure they are completely cold and use a large, sharp knife like a chef’s knife so you can cut completely across the width of them. Wipe off the knife between each cut!

Peanut Butter Swirl Brownies | katiebirdbakes

The best part is when you finally get to sink your teeth into that first bite of fudgy, peanut butter swirl brownie decadence. The richness and sweet chocolate depth of the brownie contrasts beautifully with the creamy, salty peanut butter.

These are definitely not diet food…but they are worth it.

More Brownie Recipes

Peanut Butter Swirl Brownies | katiebirdbakes
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4.64 from 11 votes

Peanut Butter Swirl Brownies

The ultimate fudgy dark chocolate brownies swirled with salty, creamy peanut butter on top! These peanut butter swirl brownies are truly decadent.
Prep Time20 minutes
Cook Time35 minutes
Total Time55 minutes
Course: Dessert
Cuisine: American
Keyword: brownies, peanut butter
Servings: 16 brownies
Author: Katiebird Bakes

Equipment

  • 8×8 inch pan

Ingredients

  • 4 oz dark chocolate, chopped (112g – about 3/4 cup)
  • ½ cup unsalted butter (113g)
  • ½ cup granulated sugar (100g)
  • ½ cup brown sugar, packed (100g)
  • 2 large eggs
  • 1 teaspoon pure vanilla extract (4g)
  • cup all-purpose flour (80g)
  • ¼ cup cocoa powder (21g)
  • 1 teaspoon salt (3g)
  • ½ teaspoon espresso powder (1g)
  • ¼ cup natural salted creamy peanut butter**, warmed until pourable (67g)

Instructions

  • Preheat your oven to 325 degrees F. Grease an 8×8 square pan or line with parchment paper. Set aside.
  • In a large bowl set in the top of a double boiler, or in the microwave in 30 second increments, melt the dark chocolate and butter, stirring occasionally, until smooth and glossy. Turn off heat, whisk in granulated and brown sugar, and let cool slightly.
  • Whisk in the eggs one at a time until fully combined, followed by the vanilla.
  • In a medium bowl, whisk together flour, cocoa powder, salt, and espresso powder.
  • Add dry ingredients to the wet and stir together just until a stiff batter forms (this is thicker than normal brownie batter!).
  • Scrape the batter into the prepared pan. Dollop small spoonfuls of the peanut butter evenly over the batter, then swirl with a toothpick until desired pattern is reached.
  • Bake brownies for 35-40 minutes, until a toothpick inserted in the center comes out with just a few crumbs attached.
  • Let brownies cool for a few minutes, then transfer to the fridge on top of a tea towel to cool completely in the pan. Store in the fridge for maximum fudginess!

Notes

*If you’d like, you can substitute ¼ cup (30 grams) of chickpea/garbanzo bean flour for ¼ cup or 30 grams of the all-purpose flour. The results are the same!
**For best swirl, use a natural peanut butter with only peanuts and salt as the ingredients.  The more liquid texture of natural peanut butter produces the best swirl.  Shelf stable peanut butter can be substituted if desired.
Brownies will keep, well-wrapped in the fridge for utmost fudginess, for up to 5 days.

Like this peanut butter brownies recipe?  Please rate it and leave a comment or tag me on Instagram @katiebirdbakes, and sign up for my email list to receive my recipes straight to your inbox every time I post!

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40 Comments

  1. How many people can these brownies feed? Because I need to bake these for over 30 kids in 2 days and I’m stressed out. Thank you Katie!

  2. 3 stars
    I made this brownie twice.
    The cooking time is much tooo long. First time I have reduced cooking time but it wasnt enough. Second time i baked the brownie for 25 min and it is still too long. I can’t imaging cooking this small brownie for 40 min
    Nice idea but i won’t be doing this brownie third time 😕
    Brownie too thin for me as well.
    Anyway thank you for the recipe I def like the idea with the peanut butter 👍🏽

    1. Thanks for the review, Cami – please do note the lower oven temperature called for in this recipe (325F) which is why these brownies bake longer. I hope you find a recipe you like!

  3. Hi Katie, I have a question about the peanut butter swirl. During baking, it bubbled up like crazy and my beautiful swirly pattern was ruined so much so that by the end it was covered very unevenly. Another thing is my brownies were really thin, way thinner than yours, even though my tray is also 8 by 8 in. Would adding a bit of baking powder help with that? Thank you for the help in advance, these are so delicious otherwise!

    1. Hey Kalina, hmm what kind of peanut butter did you use? I’ve made this recipe with both shelf-stable and natural peanut butter, and haven’t had issues although it definitely does bubble a little bit in the oven. Just check to make sure you aren’t using more than 1/4 cup – I imagine if there were more of it, the melting and bubbling could definitely be an issue. On the thinness, I’m trying to think of why there would be a volume issue. You double checked all of the measurements, right? The only thing I can think of is that maybe there wasn’t enough cocoa powder/flour or perhaps not enough melted chocolate.

  4. 3 stars
    Mine were not fudgy and used the recommended peanut butter but it seemed to dry out when it was cooked. Not what I was expecting.

  5. 5 stars
    Omg!! I absolutely love brownies and I’ve tried so many recipes including black bean recipes but these were just Aaaaamazing! They were sooo gooey,fudgy (used 100% cocao)and chocolatey and the combination with the peanut butter was just heavenly!! I’ll definitely try these with chickpea flour next time but thank you so much for sharing!

  6. 5 stars
    These were delicious! Very fudgey and good cold or hot. Followed the recipe exactly and kept them in the fridge as recommended. Will make again!

  7. I made these for my boyfriends birthday today. Peanut butter and chocolate are his favorite combination. I was a bit disappointed because these brownies are more of a “cake” texture than a brownie. I was hoping for more of an actual brownie rather than a cake. Also very very rich. Keep that in mind if you decide to make these. They are very good other than that!

  8. Hi Katie! I’d like to make a big batch of these in advance, is it possible to freeze the sliced brownies after baking, then reheat them in the oven? Or would you suggest another method? Thanks!

    1. Hi Lia – you definitely can freeze them, but I would just leave them out at room temperature for 6-8 hours before serving so they have a chance to defrost! No need to rebake them, I think that would dry them out. Enjoy!

  9. 5 stars
    Loved the PB swirl brownies….my family loved them a lot. Brownies disappeared in minutes.
    Love from India!!

  10. 5 stars
    SO. GOOD.

    I was looking for a PB swirl brownie that didn’t require me to mix in additional melted butter or sugar etc with the PB – and this was it! I doubled the recipe for a 9×13 pan, used AP flour only and omitted the espresso powder. Love the fudgy brownie centers, and love that the PB swirl stays creamy after baking.

    I shared the brownies with some friends and wish I had kept more for myself!

  11. I want to try these, but would it change the flavor a lot if I leave the expresso powder out? They sound delicious! I just don’t do coffee or much caffeine.

      1. 5 stars
        Love them! I use chunky natural pb, since that is the only pb I ever use. Delicious, and easy!

  12. 5 stars
    I heard about this recipe through The Crumb podcast. Made it with AP flour only and omg it was so good and the very definition of fudginess + so pretty thanks to the swirl 😍

  13. I left a similar question on your IG for this recipe, but I don’t know which one you might see. I want to use dried cherries, pretzels, chocolate chunks and peanut butter to add up to the 1 1/2 cups the original recipe calls for. Obviously a half cup of peanut butter weighs more than a half cup of pretzels or dried cherries, so how do I do the math? It would be so easy if the recipe said, “your mix-ins should weigh 150g ,” but instead it uses 1 1/2 cups. Please help a clueless not-quite-newbie baker.

    1. Hey Laurie – I know we talked on Instagram about this but wanted to leave a written comment here in case anyone else has the same question – this is a halved scaled down version of the original recipe, so if you want to do add-ins I would limit them to 3/4 cup. So you should do 1/2 cup mix of the other mix-ins and then the 1/4 cup of peanut butter swirled over top. Thanks!